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(NVIDIA) Fan-Based-Heatsink Designs are probably wrong. (suck, don't blow ! heatfins direction)
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Skybuck Flying
Aug 18, 2012, 1:19:11 PM8/18/12
to
Hello,
I am starting to believe that NVIDIA's Fan-Based-Heatsink Designs like the
recent GTX 690 are totally wrong !
And here is why:
The heatsink fins are placed in the same direction as the airflow. This will
cause dust to easily get stuck between the heatsink fins and especially in
front of it.
THIS IS WRONG. This will cause the heatsink to get full of tiny little hair
pieces and dust particles.
HERE IS HOW TO RESOLVE/IMPROVE THE SITUATION:
Place the heatsink fins 90 degrees turned so that the overflow must go OVER
the heatsink fins and not in between.
So here is a picture to show the wrong situation and the better situation:
top view of card when place on table:
1. WRONG DESIGN:
HEATSINK FINS:
---------------------
------------------------
+-------+
--------------------- <----- airflow | FAN
<--airflow--- -----------------------
+-------+
---------------------
-----------------------
2. BETTER DESIGN:
| | | | | |
|
| | | | +------+ | | |
| | | | <---- airflow | fan | <--- airflow | | |
| | | | +------+ | | |
| | | | | | |
This better design should hopefully and be designed in such a way... that
air/heat GETS sucked out of the heatfins by blowing air OVER IT and not in
between... to reduce the chance of stuff getting stuck in it !
So there should be some room OVER the heatfins to be able to blow air
through it.
Bye,
Skybuck.
I am starting to believe that NVIDIA's Fan-Based-Heatsink Designs like the
recent GTX 690 are totally wrong !
And here is why:
The heatsink fins are placed in the same direction as the airflow. This will
cause dust to easily get stuck between the heatsink fins and especially in
front of it.
THIS IS WRONG. This will cause the heatsink to get full of tiny little hair
pieces and dust particles.
HERE IS HOW TO RESOLVE/IMPROVE THE SITUATION:
Place the heatsink fins 90 degrees turned so that the overflow must go OVER
the heatsink fins and not in between.
So here is a picture to show the wrong situation and the better situation:
top view of card when place on table:
1. WRONG DESIGN:
HEATSINK FINS:
---------------------
------------------------
+-------+
--------------------- <----- airflow | FAN
<--airflow--- -----------------------
+-------+
---------------------
-----------------------
2. BETTER DESIGN:
| | | | | |
|
| | | | +------+ | | |
| | | | <---- airflow | fan | <--- airflow | | |
| | | | +------+ | | |
| | | | | | |
This better design should hopefully and be designed in such a way... that
air/heat GETS sucked out of the heatfins by blowing air OVER IT and not in
between... to reduce the chance of stuff getting stuck in it !
So there should be some room OVER the heatfins to be able to blow air
through it.
Bye,
Skybuck.
Skybuck Flying
Aug 18, 2012, 1:26:01 PM8/18/12
to
Additional:
Since my horror experience with the 7900 gtx cards I am afraid to buy
graphics cards with the nvidia heatfins direction.
I am afraid that the graphics cards heatsink fins will get full of dust and
stop to function !
My newest passively cooled graphics card is actually also an nvidia/asus
design. Where the heatfins are in the direction against the airflow.
So far there is probably no dust in side of it... or very little... which
seems to be much better.
If nvidia wants my bussiness back they will have to design cards which can
operate for the long term, without requiring any cleaning what so ever.
I am not going to open up my PC and risk damage during cleaning operations.
NO CLEANING operations should be necessary.
THEREFORE nvidia must design graphics cards which will operate for a long
time... 5 to 10 years of blowing/sucking air.
Perhaps the heatfin direction that I proposed is less optimal in the short
term... but will probably be optimal in the long term.
Therefore my advise to nvidia which they hopefully already have:
1. BUILD A DUST/PARTICLE LAB.
2. TEST the graphics card heatsink design for as long as possible... and
test the situation with dust build up.
3. Build the graphics cards which has the least problems with dust build up.
Otherwise you can go to hell... I do not ever want to face overheating
problems because of gpu overheat/heatsink full problems ! ;) :)
Bye,
Skybuck.
Since my horror experience with the 7900 gtx cards I am afraid to buy
graphics cards with the nvidia heatfins direction.
I am afraid that the graphics cards heatsink fins will get full of dust and
stop to function !
My newest passively cooled graphics card is actually also an nvidia/asus
design. Where the heatfins are in the direction against the airflow.
So far there is probably no dust in side of it... or very little... which
seems to be much better.
If nvidia wants my bussiness back they will have to design cards which can
operate for the long term, without requiring any cleaning what so ever.
I am not going to open up my PC and risk damage during cleaning operations.
NO CLEANING operations should be necessary.
THEREFORE nvidia must design graphics cards which will operate for a long
time... 5 to 10 years of blowing/sucking air.
Perhaps the heatfin direction that I proposed is less optimal in the short
term... but will probably be optimal in the long term.
Therefore my advise to nvidia which they hopefully already have:
1. BUILD A DUST/PARTICLE LAB.
2. TEST the graphics card heatsink design for as long as possible... and
test the situation with dust build up.
3. Build the graphics cards which has the least problems with dust build up.
Otherwise you can go to hell... I do not ever want to face overheating
problems because of gpu overheat/heatsink full problems ! ;) :)
Bye,
Skybuck.
Skybuck Flying
Aug 18, 2012, 1:36:48 PM8/18/12
to
One last explanantion/addition for any potential dumbos out there to explain
the "suck, don't blow" part of the title.
The idea is to:
BLOW air OVER heat fins.
Hopefully this will create some kind of suckage effect over the heatfins and
suck heat from between the heat fins and blow it away.
This might also have a beneficial effect of sucking any dust/hair particles
out of it and blowing it out.
That's the idea at least... which would be very nice.
I am not sure if it will work like that in practice... since there is no
opening on the other side of the heat fin to suck from....
So maybe some kind of vacuum would result from it...
If that is a good or bad thing remains to be seen/tested.
Very maybe openings could create on the other side... but that would
probably start to suck dust between the fins which would be bad.
So experimenting with this idea is required to see what works best long
term.
My only worry would be that the opposite might happen, maybe dust will start
to fall down between the heatfins....
What will happen in reality I don't know...
THIS REMAINS TO BE TESTED ! ;) =D
Perhaps someday... a dust particle simulator might show what happens ;) :)
Bye,
Skybuck :)
the "suck, don't blow" part of the title.
The idea is to:
BLOW air OVER heat fins.
Hopefully this will create some kind of suckage effect over the heatfins and
suck heat from between the heat fins and blow it away.
This might also have a beneficial effect of sucking any dust/hair particles
out of it and blowing it out.
That's the idea at least... which would be very nice.
I am not sure if it will work like that in practice... since there is no
opening on the other side of the heat fin to suck from....
So maybe some kind of vacuum would result from it...
If that is a good or bad thing remains to be seen/tested.
Very maybe openings could create on the other side... but that would
probably start to suck dust between the fins which would be bad.
So experimenting with this idea is required to see what works best long
term.
My only worry would be that the opposite might happen, maybe dust will start
to fall down between the heatfins....
What will happen in reality I don't know...
THIS REMAINS TO BE TESTED ! ;) =D
Perhaps someday... a dust particle simulator might show what happens ;) :)
Bye,
Skybuck :)
MrTallyman
Aug 18, 2012, 3:18:36 PM8/18/12
to
On Sat, 18 Aug 2012 19:19:11 +0200, "Skybuck Flying"
They suck so that YOU still have direct access to clean the tines of
the heat sink. If they blew, the heat sink would get plugged up in a
place under the fan, and you would have to remove the fan to clean it.
Now shut up and go away and stop making posts which you are then the
only idiot who responds to it the first 5 times!
Grow up, child! You are immature AND stupid. Get over it. Leave US
out of it.
You are a very particular type of Usenet idiot, and you are blind to
it.
<Window...@DreamPC2006.com> wrote:
>
>I am starting to believe
You are an idiot.
>
>I am starting to believe
They suck so that YOU still have direct access to clean the tines of
the heat sink. If they blew, the heat sink would get plugged up in a
place under the fan, and you would have to remove the fan to clean it.
Now shut up and go away and stop making posts which you are then the
only idiot who responds to it the first 5 times!
Grow up, child! You are immature AND stupid. Get over it. Leave US
out of it.
You are a very particular type of Usenet idiot, and you are blind to
it.
John Larkin
Aug 18, 2012, 3:59:41 PM8/18/12
to
On Sat, 18 Aug 2012 19:19:11 +0200, "Skybuck Flying"
<Window...@DreamPC2006.com> wrote:
<Window...@DreamPC2006.com> wrote:
Even better, aim the fan at something else a foot or two away.
You are of course assuming that you know more about cooling a CPU than
all the people who currently make a living cooling CPUs, including the
MEs in charge of thermal design at Nvidia.
I have this theory that the fins of a heat sink should reduce a fan's
free-flow rate by 50% for optimum heat transfer.
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Flasherly
Aug 18, 2012, 7:33:13 PM8/18/12
to
On Aug 18, 3:59 pm, John Larkin
reduction of motor shaft speed, equal to chambering outflow, or both
chambered, as opposed to an effective vacuum, which might further
indicate where motor design is outside operational efficiency,
irrelevant of equipment MTBF, and provided there's salience to some
residual mean temperature for cooling to be a factor in coincident
significance to ascribe at the proposed structural end as an operative
upon RPM.
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>
> I have this theory that the fins of a heat sink should reduce a fan's
> free-flow rate by 50% for optimum heat transfer.
Unless chambered to stop air flowing in for an arbitrary 10-25%
>
> I have this theory that the fins of a heat sink should reduce a fan's
> free-flow rate by 50% for optimum heat transfer.
reduction of motor shaft speed, equal to chambering outflow, or both
chambered, as opposed to an effective vacuum, which might further
indicate where motor design is outside operational efficiency,
irrelevant of equipment MTBF, and provided there's salience to some
residual mean temperature for cooling to be a factor in coincident
significance to ascribe at the proposed structural end as an operative
upon RPM.
Rheilly Phoull
Aug 18, 2012, 7:57:45 PM8/18/12
to
doctor) ??
Robert Macy
Aug 18, 2012, 8:19:48 PM8/18/12
to
On Aug 18, 12:59 pm, John Larkin
instead about the air's thermal mass, thermal resistance form metal to
bulk air. and you see you're left with characteristics of the heat
sink, not the characteristics of the fan.
As a mind argument enfisionone hell of a powerful fan. Now block that
to half flow, what do you have? versus an 'underpowered' fan that is
blocked to half flow. .
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> I have this theory that the fins of a heat sink should reduce a fan's
> free-flow rate by 50% for optimum heat transfer.
>
optimum heat transfer? not sure what the criteria would be, but think
> I have this theory that the fins of a heat sink should reduce a fan's
> free-flow rate by 50% for optimum heat transfer.
>
instead about the air's thermal mass, thermal resistance form metal to
bulk air. and you see you're left with characteristics of the heat
sink, not the characteristics of the fan.
As a mind argument enfisionone hell of a powerful fan. Now block that
to half flow, what do you have? versus an 'underpowered' fan that is
blocked to half flow. .
Message has been deleted
SC Tom
Aug 18, 2012, 9:31:43 PM8/18/12
to
"DK" <d...@no.email.thankstospam.net> wrote in message
news:BtWXr.34005$Yf7....@newsfe16.iad...
> In article <tnsv2811oj6gplej7...@4ax.com>, John Larkin
> <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>>
>>You are of course assuming that you know more about cooling a CPU than
>>all the people who currently make a living cooling CPUs, including the
>>MEs in charge of thermal design at Nvidia.
>
> When a video driver installation takes 200 MB on a hard drive
>>
>>You are of course assuming that you know more about cooling a CPU than
>>all the people who currently make a living cooling CPUs, including the
>>MEs in charge of thermal design at Nvidia.
>
> and is still full of bugs, there is every reason to question designers'
> competence.
>
That's a different group of engineers. I doubt seriously if the design
engineers are also the software engineers, although there is probably *some*
collaboration between the two groups.
The design engineers I worked with had a motto: "If it ain't broke, redesign
it!" No such thing as leaving well enough alone :-)
--
SC Tom
Quadibloc
Aug 18, 2012, 8:54:54 PM8/18/12
to
On Aug 18, 11:19 am, "Skybuck Flying" <Windows7I...@DreamPC2006.com>
wrote:
> Place the heatsink fins 90 degrees turned so that the overflow must go OVER
> the heatsink fins and not in between.
The reason the heatsink _has_ fins is to maximize the contact area
between the heatsink and the air. So you also want to maximize the
velocity of the air in proximity to every part of the heatsink, so
that there is a larger temperature difference over as much of that
large contact area as possible.
One puts a dust filter in front of the intake vent to keep dust out of
the fins, although dust generally does not collect where there is a
violent wind.
What you really want to do, though, is use a working fluid other than
air which can carry more heat away. Of course, the Montreal Protocol
because of the ozone layer makes that more complicated; the other
alternative requires careful precautions because it becomes
electrically conductive very easily by dissolving material.
But a third alternative to setting up a refrigeration system and using
chilled water would be using chilled mineral oil. Of course, there,
flammability is a problem, although the fractions typically used for
such purposes aren't too bad...
John Savard
wrote:
> Place the heatsink fins 90 degrees turned so that the overflow must go OVER
> the heatsink fins and not in between.
between the heatsink and the air. So you also want to maximize the
velocity of the air in proximity to every part of the heatsink, so
that there is a larger temperature difference over as much of that
large contact area as possible.
One puts a dust filter in front of the intake vent to keep dust out of
the fins, although dust generally does not collect where there is a
violent wind.
What you really want to do, though, is use a working fluid other than
air which can carry more heat away. Of course, the Montreal Protocol
because of the ozone layer makes that more complicated; the other
alternative requires careful precautions because it becomes
electrically conductive very easily by dissolving material.
But a third alternative to setting up a refrigeration system and using
chilled water would be using chilled mineral oil. Of course, there,
flammability is a problem, although the fractions typically used for
such purposes aren't too bad...
John Savard
Flasherly
Aug 18, 2012, 10:50:53 PM8/18/12
to
On Aug 18, 7:57 pm, Rheilly Phoull <rhei...@bigslong.com> wrote:
>
> Umm, you would not perchance be employed in a government position (spin
> doctor) ??
If I had my druthers, I'd as rather gainfully, that is contractually
>
> Umm, you would not perchance be employed in a government position (spin
> doctor) ??
and under government auspices, to be on your tax dollar, sic, whereby
to impose mandatory interpolation of required observances, forthwith
said forthrightly, such that as an agreeable conscientious citizen,
I'm sure you are, there could be no other possible meaning given you
to mistake my greater schemes.
--
'Within a judicial system, the only worse case scenario, other than a
divorce, is a lawyer in full possession and faculty of doctorates both
in law and philosophy.' -Socrates, A Known Drinker of Hemlock
Mike Tomlinson
Aug 18, 2012, 10:49:03 PM8/18/12
to
En el artículo <BtWXr.34005$Yf7....@newsfe16.iad>, DK
<d...@no.email.thankstospam.net> escribió:
>When a video driver installation takes 200 MB on a hard drive
>and is still full of bugs, there is every reason to question designers'
>competence.
Come on. That's software vs. hardware. The engineers may design and
build superb hardware, but if the software isn't up to scratch, it's
wasted effort. Look at ATi/AMD cards, for instance. Good hardware,
lousy drivers.
--
(\_/)
(='.'=)
(")_(")
<d...@no.email.thankstospam.net> escribió:
>When a video driver installation takes 200 MB on a hard drive
>and is still full of bugs, there is every reason to question designers'
>competence.
build superb hardware, but if the software isn't up to scratch, it's
wasted effort. Look at ATi/AMD cards, for instance. Good hardware,
lousy drivers.
--
(\_/)
(='.'=)
(")_(")
John Larkin
Aug 19, 2012, 12:12:42 AM8/19/12
to
John Larkin
Aug 19, 2012, 12:18:47 AM8/19/12
to
On Sat, 18 Aug 2012 17:19:48 -0700 (PDT), Robert Macy
<robert...@gmail.com> wrote:
>On Aug 18, 12:59 pm, John Larkin
><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>> I have this theory that the fins of a heat sink should reduce a fan's
>> free-flow rate by 50% for optimum heat transfer.
>>
>
>optimum heat transfer? not sure what the criteria would be,
Minimum theta would do.
<robert...@gmail.com> wrote:
>On Aug 18, 12:59 pm, John Larkin
><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>> I have this theory that the fins of a heat sink should reduce a fan's
>> free-flow rate by 50% for optimum heat transfer.
>>
>
>optimum heat transfer? not sure what the criteria would be,
but think
>instead about the air's thermal mass, thermal resistance form metal to
>bulk air. and you see you're left with characteristics of the heat
>sink, not the characteristics of the fan.
>
>As a mind argument enfisionone hell of a powerful fan. Now block that
>to half flow, what do you have? versus an 'underpowered' fan that is
>blocked to half flow. .
around the fins, not through them (as Skybuck suggests) and the air
does no good. And if you block all the air flow, it does no good. So
the amount of airflow restriction that results in the lowest theta
must be somewhere between those two extremes. Dead center is a pretty
good guess.
Message has been deleted
Jeff Liebermann
Aug 19, 2012, 1:05:11 AM8/19/12
to
On Sat, 18 Aug 2012 12:59:41 -0700, John Larkin
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>I have this theory that the fins of a heat sink should reduce a fan's
>free-flow rate by 50% for optimum heat transfer.
If the input and output temperatures were the same, that might be
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>I have this theory that the fins of a heat sink should reduce a fan's
>free-flow rate by 50% for optimum heat transfer.
true. It might also be true if you consider the reduction in free
flow rate caused by the back pressure due to the head sink obstructing
the air flow.
However, air expands when heated, causing an increase in air flow at
the exhaust end. That's why the exhaust port for a heat removal
system is larger than the intake. My guess(tm) is that the increased
exhaust air flow caused by heating is much larger than the reduction
in intake air flow caused by the fins getting in the way.
On the original assertion, that it's better to suck than to blow,
methinks that's wrong. You can demonstrate this with a dirty
computer. Take a vacuum cleaner and try to remove the dust by
sucking. Most of it will still be in the machine when you're done.
Now, put the hose on the same vacuum cleaner exhaust and blow the dust
out of the machine. Notice that remaining dust is effectively blown
all over the room.
It's dispersion versus concentration. When sucking, one pulls air
from the sides and from all around the heat sink, including air that
does not need cooling. This makes the fan work harder moving excess
air, leaving less air flow for between the heatsink fins. Turn the
fan around and blow air at the heat sink, and the entire air flow is
involved in cooling the fins.
Similarly, you can demonstrate the effect by comparing the CPU
temperatures with the fan in the normal position (blowing air down
towards the heat sink), versus flipping the fan over and sucking air
out. I did this with a Pentium 4 dual core. I forgot the measured
temperatures, but the difference was substantial.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jeff Liebermann
Aug 19, 2012, 1:17:37 AM8/19/12
to
On Sat, 18 Aug 2012 17:54:54 -0700 (PDT), Quadibloc
<jsa...@ecn.ab.ca> wrote:
>But a third alternative to setting up a refrigeration system and using
>chilled water would be using chilled mineral oil. Of course, there,
>flammability is a problem, although the fractions typically used for
>such purposes aren't too bad...
What you want is immersion cooling:
<jsa...@ecn.ab.ca> wrote:
>But a third alternative to setting up a refrigeration system and using
>chilled water would be using chilled mineral oil. Of course, there,
>flammability is a problem, although the fractions typically used for
>such purposes aren't too bad...
<http://images.bit-tech.net/content_images/2009/12/the-hardware-hall-of-fame/hof9.jpg>
<http://www.bit-tech.net/news/2008/10/23/hardcore-computer-launches-immersion-cooled-pcs/1>
<http://www.maximumpc.com/article/features/hardcorepc_reactor/>
<http://hackedgadgets.com/wp-content/2/Mineral_Oil_Submerged_Computer_1.jpg>
<http://img.photobucket.com/albums/v53/pinkfloyd33/DSCN2748.jpg>
<http://www.youtube.com/watch?v=PtufuXLvOok>
<http://smallformfactors.com/articles/immersion-form-factor-server-class-systems/>
Build a leak proof package, insert computer, fill with fluorinert,
mineral oil, anti-freeze, distilled water, or whatever and it will
redistribute the heat to a much larger mass and surface area.
Timothy Daniels
Aug 19, 2012, 2:35:29 AM8/19/12
to
"Jeff Liebermann" wrote:
> [.............]
Given the same mass/sec flow of air over the fins of a heatsink,
the best heat transfer is by blowing due to the greater turbulence -
which disturbs the boundary layer of air that lies in contact with
the fins and puts more flowing air in direct contact with the surface
of the fins. In the case where the fins rise up away from the source
of the heat, it's best to blow downward from the ends of the fins
toward the source of the heat. IOW, the air should move in a
direction opposite to the heat flow.
This principle is not only used in heat transfer systems, but also in
biological systems in oxygen transfer through membranes - as in
fish gills where the blood moves across the gill membrane in a
direction opposite to the flow of water. The basis of this principle
lies in the finite heat (or gas) capacity of a fluid and that greatest
heat (or gas) flow occurs as a linear function of the difference of
temperature (or gas concentration) between 2 bodies. Apply a little
calculus, and the principle of opposing flows results. This design
principle was recently seen when I opened up the case of a friend's
PC to clean it out: The cooling fins for the CPU rose up from the CPU,
and the cooling fan blew air down along the fins toward the CPU.
Obviously, the designer had paid attention during college freshman
physics.
*TimDaniels*
> [.............]
> On the original assertion, that it's better to suck than to blow,
> methinks that's wrong. .....
Given the same mass/sec flow of air over the fins of a heatsink,
the best heat transfer is by blowing due to the greater turbulence -
which disturbs the boundary layer of air that lies in contact with
the fins and puts more flowing air in direct contact with the surface
of the fins. In the case where the fins rise up away from the source
of the heat, it's best to blow downward from the ends of the fins
toward the source of the heat. IOW, the air should move in a
direction opposite to the heat flow.
This principle is not only used in heat transfer systems, but also in
biological systems in oxygen transfer through membranes - as in
fish gills where the blood moves across the gill membrane in a
direction opposite to the flow of water. The basis of this principle
lies in the finite heat (or gas) capacity of a fluid and that greatest
heat (or gas) flow occurs as a linear function of the difference of
temperature (or gas concentration) between 2 bodies. Apply a little
calculus, and the principle of opposing flows results. This design
principle was recently seen when I opened up the case of a friend's
PC to clean it out: The cooling fins for the CPU rose up from the CPU,
and the cooling fan blew air down along the fins toward the CPU.
Obviously, the designer had paid attention during college freshman
physics.
*TimDaniels*
Tim Williams
Aug 19, 2012, 2:56:38 AM8/19/12
to
"Timothy Daniels" <Spam...@NoSuchDomain.com> wrote in message
news:tfKdnTtI9v-qFK3N...@earthlink.com...
not-quite-radial, in an X pattern around the center. It looks like
extrusion oriented axially (axis normal to the processor face), rather
than transverse. The fan blows air over the center and fins.
At 100% CPU I get 42C tops, so it seems to be doing its job. Nothing
special, a dual core 3.2GHz Athalon II. It's also entirely possible AMD
(or whoever they contracted to make them) doesn't know their physics.
Note that heat transfer by volume isn't usually the goal, so much as
minimum temperature is. In a counterflow setup, the hottest part of the
heatsink is cooled by the hottest air. If you flip it around, the hottest
part of the heatsink gets cooled by the coolest air, achieving the highest
heat flux for a given surface area and temperature difference -- more
power density, at some expense to mass flow and pumping loss. You might
avoid this, for example, if you had to use pure nitrogen (or helium, for
that matter) for some process, minimizing the gas flow to keep operating
cost down.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
news:tfKdnTtI9v-qFK3N...@earthlink.com...
> This design
> principle was recently seen when I opened up the case of a friend's
> PC to clean it out: The cooling fins for the CPU rose up from the CPU,
> and the cooling fan blew air down along the fins toward the CPU.
> Obviously, the designer had paid attention during college freshman
> physics.
Oddly, my new, stock heatsink is designed with fins arranged
> principle was recently seen when I opened up the case of a friend's
> PC to clean it out: The cooling fins for the CPU rose up from the CPU,
> and the cooling fan blew air down along the fins toward the CPU.
> Obviously, the designer had paid attention during college freshman
> physics.
not-quite-radial, in an X pattern around the center. It looks like
extrusion oriented axially (axis normal to the processor face), rather
than transverse. The fan blows air over the center and fins.
At 100% CPU I get 42C tops, so it seems to be doing its job. Nothing
special, a dual core 3.2GHz Athalon II. It's also entirely possible AMD
(or whoever they contracted to make them) doesn't know their physics.
Note that heat transfer by volume isn't usually the goal, so much as
minimum temperature is. In a counterflow setup, the hottest part of the
heatsink is cooled by the hottest air. If you flip it around, the hottest
part of the heatsink gets cooled by the coolest air, achieving the highest
heat flux for a given surface area and temperature difference -- more
power density, at some expense to mass flow and pumping loss. You might
avoid this, for example, if you had to use pure nitrogen (or helium, for
that matter) for some process, minimizing the gas flow to keep operating
cost down.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
upsid...@downunder.com
Aug 19, 2012, 4:06:56 AM8/19/12
to
On Sat, 18 Aug 2012 22:05:11 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:
>However, air expands when heated, causing an increase in air flow at
>the exhaust end. That's why the exhaust port for a heat removal
>system is larger than the intake. My guess(tm) is that the increased
>exhaust air flow caused by heating is much larger than the reduction
>in intake air flow caused by the fins getting in the way.
The air density drops from 1.2 kg/m� at +25 C to about 0.6 kg/m� at
+325 C, so yes, it might make sense to double the exhaust cross
section area.
However, for practical semiconductor cooling applications, with intake
temperature at +25 C and exhaust temperatures below +60 C, air density
is about 1.07 kg/m�, an expansion is only about 10 %. I doubt it
would make much sense to try to optimize exhaust areas.
wrote:
>However, air expands when heated, causing an increase in air flow at
>the exhaust end. That's why the exhaust port for a heat removal
>system is larger than the intake. My guess(tm) is that the increased
>exhaust air flow caused by heating is much larger than the reduction
>in intake air flow caused by the fins getting in the way.
+325 C, so yes, it might make sense to double the exhaust cross
section area.
However, for practical semiconductor cooling applications, with intake
temperature at +25 C and exhaust temperatures below +60 C, air density
is about 1.07 kg/m�, an expansion is only about 10 %. I doubt it
would make much sense to try to optimize exhaust areas.
upsid...@downunder.com
Aug 19, 2012, 4:57:37 AM8/19/12
to
On Sun, 19 Aug 2012 01:56:38 -0500, "Tim Williams"
<tmor...@charter.net> wrote:
>Note that heat transfer by volume isn't usually the goal, so much as
>minimum temperature is. In a counterflow setup, the hottest part of the
>heatsink is cooled by the hottest air. If you flip it around, the hottest
>part of the heatsink gets cooled by the coolest air, achieving the highest
>heat flux for a given surface area and temperature difference -- more
>power density, at some expense to mass flow and pumping loss. You might
>avoid this, for example, if you had to use pure nitrogen (or helium, for
>that matter) for some process, minimizing the gas flow to keep operating
>cost down.
Why not use compressed/expanded air for this purpose ? Using a piston
<tmor...@charter.net> wrote:
>Note that heat transfer by volume isn't usually the goal, so much as
>minimum temperature is. In a counterflow setup, the hottest part of the
>heatsink is cooled by the hottest air. If you flip it around, the hottest
>part of the heatsink gets cooled by the coolest air, achieving the highest
>heat flux for a given surface area and temperature difference -- more
>power density, at some expense to mass flow and pumping loss. You might
>avoid this, for example, if you had to use pure nitrogen (or helium, for
>that matter) for some process, minimizing the gas flow to keep operating
>cost down.
compressor to compress the air to a few bars, the air gets quite hot,
then let it go through a heat exchanger to get rid of most of the heat
and cool the pressurized air closer to ambient temperature.
Let the air expand to normal ambient pressure and the air temperature
is now well below ambient temperature and let it flow through
semiconductor heatsinks to the environment.
To avoid problems with dust and condensation, a closed loop might make
sense, but of course, now the heat exchanger would also have to
dissipate the heat from the semiconductor. However, the heat exchanger
can be remotely located and it can have much higher temperatures than
the semiconductors, getting rid of the heat into the environment would
be easier.
Martin Brown
Aug 19, 2012, 5:22:54 AM8/19/12
to
On 19/08/2012 05:18, John Larkin wrote:
> On Sat, 18 Aug 2012 17:19:48 -0700 (PDT), Robert Macy
> <robert...@gmail.com> wrote:
>
>> On Aug 18, 12:59 pm, John Larkin
>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>>> I have this theory that the fins of a heat sink should reduce a fan's
>>> free-flow rate by 50% for optimum heat transfer.
>>>
>>
>> optimum heat transfer? not sure what the criteria would be,
>
> Minimum theta would do.
>
>
> but think
>> instead about the air's thermal mass, thermal resistance form metal to
>> bulk air. and you see you're left with characteristics of the heat
>> sink, not the characteristics of the fan.
>>
>> As a mind argument enfisionone hell of a powerful fan. Now block that
>> to half flow, what do you have? versus an 'underpowered' fan that is
>> blocked to half flow. .
>
> If the heat sink doesn't reduce air flow at all, the air is going
> around the fins, not through them (as Skybuck suggests) and the air
> does no good. And if you block all the air flow, it does no good. So
More to the point if the heatsink fins are not thick enough to conduct
> On Sat, 18 Aug 2012 17:19:48 -0700 (PDT), Robert Macy
> <robert...@gmail.com> wrote:
>
>> On Aug 18, 12:59 pm, John Larkin
>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>>> I have this theory that the fins of a heat sink should reduce a fan's
>>> free-flow rate by 50% for optimum heat transfer.
>>>
>>
>> optimum heat transfer? not sure what the criteria would be,
>
> Minimum theta would do.
>
>
> but think
>> instead about the air's thermal mass, thermal resistance form metal to
>> bulk air. and you see you're left with characteristics of the heat
>> sink, not the characteristics of the fan.
>>
>> As a mind argument enfisionone hell of a powerful fan. Now block that
>> to half flow, what do you have? versus an 'underpowered' fan that is
>> blocked to half flow. .
>
> If the heat sink doesn't reduce air flow at all, the air is going
> around the fins, not through them (as Skybuck suggests) and the air
> does no good. And if you block all the air flow, it does no good. So
heat away from the thing being cooled it doesn't matter how easily you
can push air through them. Equally it is no good if you get perfect
laminar airflow since then only the air touching the surface warms up
and the core air remains cool. So you have to have some turbulence and
opposition to free flow but the tricky question is how much is enough?
Something like this might be close :
====o ====o ====o
====o ====o
====o ====o ====o
(slightly tighter together than ASCII art will allow)
Airflow from left to right with a blob on the end to mix the air up.
> the amount of airflow restriction that results in the lowest theta
> must be somewhere between those two extremes. Dead center is a pretty
> good guess.
sink is proportional to the amount of cooling you get for a given design
so there is a definite bias towards not blocking off half the free air
flow. I would guess at something more like allowing 2/3 to 3/4 of free
airflow as about the best depending on the exact heatsink geometry. It
could easily be higher - easy enough to do the experiment.
I suspect the perfect shape for an optimum heatsink is rather more
complex than the typical fins we get but the designs used at present are
good enough and much easier to engineer. Heat pipes have helped
enormously with the latest generation of quiet heatsinks.
It is a sobering thought that high performance CPUs often have a heat
output per unit area that exceeds the tip of a soldering iron.
Regards,
Martin Brown
SC Tom
Aug 19, 2012, 8:36:37 AM8/19/12
to
"Jeff Liebermann" <je...@cruzio.com> wrote in message
news:g3s0381vglrf8hrn5...@4ax.com...
with the air being pulled through than it was with it being blown through.
One of the electrical engineers at work explained it this way: If the air is
being pulled through, most of the air is moving through the fin area closest
to the fan, with the lower fins (closest to the CPU) getting the least
amount of flow. Therefore the heat has to transfer through the fins before
it gets to an area where there is enough air flow to actually aid in heat
removal. But, with the air being blown down, through the fins, there is
enough back-pressure to allow the air to travel almost equally across all
fin surfaces before exiting, carrying a larger amount of heat with it. Don't
know if that's exactly how it works, but it made sense to me, and would
explain why most newer heatsinks have the air blown through rather than
pulled through the fins.
--
SC Tom
Rheilly Phoull
Aug 19, 2012, 10:51:40 AM8/19/12
to
Flasherly
Aug 19, 2012, 11:47:26 AM8/19/12
to
On Aug 19, 12:12 am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>
> Right.
I've bought about every heatsink or fan imaginable, given and within,
as another mentioned, an axiomatic engineering construct concept --
'if it's done right [in the first place], it's time to [attempt] an
improvement, [if and while not in need of entirely new construction
concepts]';- time simply follows, technologically speaking, to march
upon and then past any R&D Dept., in failure aptly to communicate, if
at least not uniquely, then an underlying implementation of adequacy
pertaining to key hard and software, constructional elements coming
in, daily, across so broad a field as computers. Where, specifically,
I see you for a fit is at a coincident juncture of heatsink fins and
augmented airflow, both being common terms to common acceptance for
pragmatic practice. The argument you have placed to ally yourself as
well follows true to the same axiom: that being one, effectively, of a
quest for perpetual motion: for so long as the key component of design
efficiency is established, widely employed to a common basis of
underlying industrial acceptance, the cost factor, then, is
effectively one which requires of me nothing more, out of my pocket,
than to advance a better sense of encouragement that such benefit, you
have chosen to propose, indeed, is of worthier consideration. Stop by
anytime if you'd like to talk, John. My office is at the top of the
stairs.
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>
> Right.
I've bought about every heatsink or fan imaginable, given and within,
as another mentioned, an axiomatic engineering construct concept --
'if it's done right [in the first place], it's time to [attempt] an
improvement, [if and while not in need of entirely new construction
concepts]';- time simply follows, technologically speaking, to march
upon and then past any R&D Dept., in failure aptly to communicate, if
at least not uniquely, then an underlying implementation of adequacy
pertaining to key hard and software, constructional elements coming
in, daily, across so broad a field as computers. Where, specifically,
I see you for a fit is at a coincident juncture of heatsink fins and
augmented airflow, both being common terms to common acceptance for
pragmatic practice. The argument you have placed to ally yourself as
well follows true to the same axiom: that being one, effectively, of a
quest for perpetual motion: for so long as the key component of design
efficiency is established, widely employed to a common basis of
underlying industrial acceptance, the cost factor, then, is
effectively one which requires of me nothing more, out of my pocket,
than to advance a better sense of encouragement that such benefit, you
have chosen to propose, indeed, is of worthier consideration. Stop by
anytime if you'd like to talk, John. My office is at the top of the
stairs.
Robert Macy
Aug 19, 2012, 11:56:05 AM8/19/12
to
On Aug 18, 9:18 pm, John Larkin
stiction layer of air. All the heat from the metal must travel through
that stiction layer [which by definition is an insulative sheet of air
on the heat sink.] Now as air moves rapidly over the HS's surface;
that stiction layer becomes thin and voila! lowers the theta. That's
why all the HS curves of temp ris for given wattage always
asymptotically approach some value as the air speed increases. It's
because the stiction layer can be thinned, but not removed.
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sat, 18 Aug 2012 17:19:48 -0700 (PDT), Robert Macy
>
> On Sat, 18 Aug 2012 17:19:48 -0700 (PDT), Robert Macy
>
> <robert.a.m...@gmail.com> wrote:
> >On Aug 18, 12:59 pm, John Larkin
> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> >> I have this theory that the fins of a heat sink should reduce a fan's
> >> free-flow rate by 50% for optimum heat transfer.
>
> >optimum heat transfer? not sure what the criteria would be,
>
> Minimum theta would do.
>
> but think
>
> >instead about the air's thermal mass, thermal resistance form metal to
> >bulk air. and you see you're left with characteristics of the heat
> >sink, not the characteristics of the fan.
>
> >As a mind argument enfisionone hell of a powerful fan. Now block that
> >to half flow, what do you have? versus an 'underpowered' fan that is
> >blocked to half flow. .
>
> If the heat sink doesn't reduce air flow at all, the air is going
> around the fins, not through them (as Skybuck suggests) and the air
> does no good. And if you block all the air flow, it does no good. So
> the amount of airflow restriction that results in the lowest theta
> must be somewhere between those two extremes. Dead center is a pretty
> good guess.
>
> --
>
> John Larkin Highland Technology Incwww.highlandtechnology.com jlarkin at highlandtechnology dot com
> >On Aug 18, 12:59 pm, John Larkin
> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> >> I have this theory that the fins of a heat sink should reduce a fan's
> >> free-flow rate by 50% for optimum heat transfer.
>
> >optimum heat transfer? not sure what the criteria would be,
>
> Minimum theta would do.
>
> but think
>
> >instead about the air's thermal mass, thermal resistance form metal to
> >bulk air. and you see you're left with characteristics of the heat
> >sink, not the characteristics of the fan.
>
> >As a mind argument enfisionone hell of a powerful fan. Now block that
> >to half flow, what do you have? versus an 'underpowered' fan that is
> >blocked to half flow. .
>
> If the heat sink doesn't reduce air flow at all, the air is going
> around the fins, not through them (as Skybuck suggests) and the air
> does no good. And if you block all the air flow, it does no good. So
> the amount of airflow restriction that results in the lowest theta
> must be somewhere between those two extremes. Dead center is a pretty
> good guess.
>
> --
>
>
> Precision electronic instrumentation
> Picosecond-resolution Digital Delay and Pulse generators
> Custom timing and laser controllers
> Photonics and fiberoptic TTL data links
> VME analog, thermocouple, LVDT, synchro, tachometer
> Multichannel arbitrary waveform generators
Doesn't lowest theta occur at MAXIMUM airflow? Think of it as a
> Precision electronic instrumentation
> Picosecond-resolution Digital Delay and Pulse generators
> Custom timing and laser controllers
> Photonics and fiberoptic TTL data links
> VME analog, thermocouple, LVDT, synchro, tachometer
> Multichannel arbitrary waveform generators
stiction layer of air. All the heat from the metal must travel through
that stiction layer [which by definition is an insulative sheet of air
on the heat sink.] Now as air moves rapidly over the HS's surface;
that stiction layer becomes thin and voila! lowers the theta. That's
why all the HS curves of temp ris for given wattage always
asymptotically approach some value as the air speed increases. It's
because the stiction layer can be thinned, but not removed.
Jeff Liebermann
Aug 19, 2012, 11:57:18 AM8/19/12
to
On Sun, 19 Aug 2012 08:47:26 -0700 (PDT), Flasherly
<Flas...@live.com> wrote:
>On Aug 19, 12:12 am, John Larkin
><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>>
>> Right.
>I've bought about every heatsink or fan imaginable, given and within,
>as another mentioned, an axiomatic engineering construct concept --
(...)
<Flas...@live.com> wrote:
>On Aug 19, 12:12 am, John Larkin
><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>>
>> Right.
>I've bought about every heatsink or fan imaginable, given and within,
>as another mentioned, an axiomatic engineering construct concept --
<http://phaser.gfxile.net/ligen/technobabble.php>
k...@att.bizzzzzzzzzzzz
Aug 19, 2012, 12:19:10 PM8/19/12
to
question is, given a fan optimize the resistance. It's an impedance matching
sort of question. Constrict the air too much, with heatsink blades and the
airflow goes down. Open it up and there is no contact between the heatsink
and air. As others have mentioned, the point isn't to reduce the boundary
layer by increasing velocity, rather to upset the boundary layer with a
turbulent flow. ...just enough turbulence to upset the boundary layer but not
so much as to restrict flow. Just enough heatsink material to transfer heat
and not so much as to restrict flow. It's not just a single variable
equation. The heat-transfer people at IBM (sat down the hall from me, moons
ago) used our electronics simulation programs to design these things. Their
sim models were just as large as ours and took just as much CPU time (hours).
John Larkin
Aug 19, 2012, 12:23:38 PM8/19/12
to
That's not what I'm talking about.
If you have some fan running full blast, with some flow-backpressure
curve, and you blow it at/through a heat sink, you could vary fin
density, fin shape, ducting, stuff like that. Maximum air flow implies
zero interaction with the heat sink fins, which will make for zero
cooling. 100% blocking by fins is zero air flow, also no cooling
attributable to the fan.
Think of it as a
>stiction layer of air. All the heat from the metal must travel through
>that stiction layer [which by definition is an insulative sheet of air
>on the heat sink.] Now as air moves rapidly over the HS's surface;
>that stiction layer becomes thin and voila! lowers the theta. That's
>why all the HS curves of temp ris for given wattage always
>asymptotically approach some value as the air speed increases. It's
>because the stiction layer can be thinned, but not removed.
The other thing going on is that the thermal resistance of the
heatsink itself, resistance along the fins or pins, starts to isolate
the extremes of the heatsink at high heat flows. You could attach the
tips of the fins to a zero-theta block and still have the thermal
resistance of the fins themselves. In real life, the baseplate lateral
theta gets to be a problem too; you get a hot spot at the chip or
mosfet or whatever, but the sink is cooler farther away. Heat sink
extrusions are apparently specified with uniform heating of the
baseplate.
For a given chip, there would be a finite theta if it were bolted to
the face of a half-the-universe-sized block of copper.
--
John Larkin Highland Technology Inc
John Larkin
Aug 19, 2012, 12:25:59 PM8/19/12
to
John Larkin
Aug 19, 2012, 12:29:33 PM8/19/12
to
>On Sat, 18 Aug 2012 12:59:41 -0700, John Larkin
><jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>>I have this theory that the fins of a heat sink should reduce a fan's
>>free-flow rate by 50% for optimum heat transfer.
>
>If the input and output temperatures were the same, that might be
>true. It might also be true if you consider the reduction in free
>flow rate caused by the back pressure due to the head sink obstructing
>the air flow.
>
>However, air expands when heated, causing an increase in air flow at
>the exhaust end.
Not enough to matter. The expansion goes as absolute temperature.
><jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>>I have this theory that the fins of a heat sink should reduce a fan's
>>free-flow rate by 50% for optimum heat transfer.
>
>If the input and output temperatures were the same, that might be
>true. It might also be true if you consider the reduction in free
>flow rate caused by the back pressure due to the head sink obstructing
>the air flow.
>
>However, air expands when heated, causing an increase in air flow at
>the exhaust end.
That's why the exhaust port for a heat removal
>system is larger than the intake.
site there. Disadvantage, if it would let air leak out. But an outlet
port restricts flow, so make it big.
Tim Williams
Aug 19, 2012, 12:30:00 PM8/19/12
to
"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
news:Zf2Yr.40356$g22....@newsfe14.iad...
sources. The peak power point (pressure * flow) occurs at a pressure of
about 25% of maximum (fully blocked) pressure. You can't operate very far
from this condition or your flow will be too slow.
If you include dynamic pressure (mass flow), fans are even more nonlinear.
Next time you have a squirrel cage type laying around, hook it up and play
with it. Put your hand over the outlet. You'll find the velocity is
great until about 1-2 diameters away, where you start feeling the force of
ram air. Within about 0.5 to 0.25 diameters, pressure is maximum, because
flow hasn't gone to zero yet, meanwhile static pressure is building. Put
your hand all the way up to block it, and static pressure goes to maximum,
but velocity goes to zero, so the power you're feeling drops sharply.
BTW, I use the example of a squirrel cage because they provide more
pressure, making a more illustrative example. Regular axial fans do as
well, and manufacturers typically provide comparable graphs.
news:Zf2Yr.40356$g22....@newsfe14.iad...
>> the amount of airflow restriction that results in the lowest theta
>> must be somewhere between those two extremes. Dead center is a pretty
>> good guess.
>
> But also very probably wrong. The volume of air going through the heat
> sink is proportional to the amount of cooling you get for a given design
> so there is a definite bias towards not blocking off half the free air
> flow. I would guess at something more like allowing 2/3 to 3/4 of free
> airflow as about the best depending on the exact heatsink geometry. It
> could easily be higher - easy enough to do the experiment.
Indeed, and add to that the fact that fans are not "resistive" air
>> must be somewhere between those two extremes. Dead center is a pretty
>> good guess.
>
> But also very probably wrong. The volume of air going through the heat
> sink is proportional to the amount of cooling you get for a given design
> so there is a definite bias towards not blocking off half the free air
> flow. I would guess at something more like allowing 2/3 to 3/4 of free
> airflow as about the best depending on the exact heatsink geometry. It
> could easily be higher - easy enough to do the experiment.
sources. The peak power point (pressure * flow) occurs at a pressure of
about 25% of maximum (fully blocked) pressure. You can't operate very far
from this condition or your flow will be too slow.
If you include dynamic pressure (mass flow), fans are even more nonlinear.
Next time you have a squirrel cage type laying around, hook it up and play
with it. Put your hand over the outlet. You'll find the velocity is
great until about 1-2 diameters away, where you start feeling the force of
ram air. Within about 0.5 to 0.25 diameters, pressure is maximum, because
flow hasn't gone to zero yet, meanwhile static pressure is building. Put
your hand all the way up to block it, and static pressure goes to maximum,
but velocity goes to zero, so the power you're feeling drops sharply.
BTW, I use the example of a squirrel cage because they provide more
pressure, making a more illustrative example. Regular axial fans do as
well, and manufacturers typically provide comparable graphs.
Flasherly
Aug 19, 2012, 1:53:03 PM8/19/12
to
>
> But also very probably wrong. The volume of air going through the heat
> sink is proportional to the amount of cooling you get for a given design
> so there is a definite bias towards not blocking off half the free air
> flow. I would guess at something more like allowing 2/3 to 3/4 of free
> airflow as about the best depending on the exact heatsink geometry. It
> could easily be higher - easy enough to do the experiment.
>
> I suspect the perfect shape for an optimum heatsink is rather more
> complex than the typical fins we get but the designs used at present are
> good enough and much easier to engineer. Heat pipes have helped
> enormously with the latest generation of quiet heatsinks.
>
> It is a sobering thought that high performance CPUs often have a heat
> output per unit area that exceeds the tip of a soldering iron.
Nope, no theta modules presently marketed, just a couple squirrel
> But also very probably wrong. The volume of air going through the heat
> sink is proportional to the amount of cooling you get for a given design
> so there is a definite bias towards not blocking off half the free air
> flow. I would guess at something more like allowing 2/3 to 3/4 of free
> airflow as about the best depending on the exact heatsink geometry. It
> could easily be higher - easy enough to do the experiment.
>
> I suspect the perfect shape for an optimum heatsink is rather more
> complex than the typical fins we get but the designs used at present are
> good enough and much easier to engineer. Heat pipes have helped
> enormously with the latest generation of quiet heatsinks.
>
> It is a sobering thought that high performance CPUs often have a heat
> output per unit area that exceeds the tip of a soldering iron.
cages and extant circular Zalman takes from a fairy good run given a
premium to pricing structures. Mass seems the byword, now-a-days,
massive as a restriction only limited by standardization among case
manufacturers. Had one recently, the typical behemoth of 7- to 1155
sockets, I picked for a proverberial song & dance, which barely missed
a nonstandard case construction I do own, within designer case
specifications by a mere 1/4", (yes, I simply had to measure it), as
opposed to a standard, however exact fit, such as Rosewill's
understudy of Antec cases. Excepting the fan -- I'd as well be
veritably ecstatic over results obtained within a reality of present
heatwick technology -- as it is, the size of an exterior case fan
ported and packaged to that CPU HS is at best, safer to defer for a
project to rewire its connection off the MB current draw and onto a PS
lead, proper.
As mentioned aside by similar instances of a P4 or AMD X2, a benefit
not only set to 107F (and lower, I reside at as low as 100F respective
to ambient temperatures), is a backtest of their efficiency to
approach flash computational processes conceivably closer to these
"soldering tips" of 130F, for as much in as least time possible then
to regain steady state 107F operational status. It's my own personal
theory, fwtw, that case designs importantly conducive to achieving
such good results, are at much an impasse the last generation of P4s
encountered before heading into nonlinear modes of augmented,
multicore processing. Extensively drilled, variously meshed and
screened, the approach has effectively advanced to a breadboard
construct from a standpoint of free air.
k...@att.bizzzzzzzzzzzz
Aug 19, 2012, 2:34:23 PM8/19/12
to
Timothy Daniels
Aug 19, 2012, 3:56:49 PM8/19/12
to
> [................]
by the fan, or calories/gm/sec. IOW, you want the most heat transferred
for the mass of air that the fan can move through the fins. (Note that the
volume of the air changes as it heats up, so mass is used in the calculations
instead of volume.)
And yes, in a counterflow situation (i.e. heat flowing through the fins in
a direction opposite to the flow of air), the coolest air contacts the coolest
portion of the fins, and the hotest air contacts the hotest part of the fins.
Since the highest heat transfer occurs where the temperature difference is
greatest, one might think that the greatest heat transfer would occur for
parallel flow situation. But no, it's the opposite when one does the calculus.
The reason is that the heat transfer in the counterflow situation works over
a longer period of time since the temperatures of the 2 media (i.e. fins and
air) remain different throughout the time of transit. In the parallel flow
situation, the greatest transfer occurs at the beginning when the 2 media
have the greatest temperature difference, but the temperature difference
falls of rapidly as the air flows toward the cooler part of the fins and the
heat transfer falls off as well.
For overclocking, where adequate cooling becomes vital, I'd go with
water cooling for the CPU. That would leave more room inside the case
for air cooling of the other components. But... that's an added expense
that one may not want to bear.
*TimDaniels*
>
> Note that heat transfer by volume isn't usually the goal, so much as
> minimum temperature is. In a counterflow setup, the hottest part of the
> heatsink is cooled by the hottest air. If you flip it around, the hottest
> part of the heatsink gets cooled by the coolest air, achieving the highest
> heat flux for a given surface area and temperature difference -- more
> power density, at some expense to mass flow and pumping loss. You might
> avoid this, for example, if you had to use pure nitrogen (or helium, for
> that matter) for some process, minimizing the gas flow to keep operating
> cost down.
>
> Tim
The goal is maximum heat transfer per gram of air for the flow provided
> Note that heat transfer by volume isn't usually the goal, so much as
> minimum temperature is. In a counterflow setup, the hottest part of the
> heatsink is cooled by the hottest air. If you flip it around, the hottest
> part of the heatsink gets cooled by the coolest air, achieving the highest
> heat flux for a given surface area and temperature difference -- more
> power density, at some expense to mass flow and pumping loss. You might
> avoid this, for example, if you had to use pure nitrogen (or helium, for
> that matter) for some process, minimizing the gas flow to keep operating
> cost down.
>
> Tim
by the fan, or calories/gm/sec. IOW, you want the most heat transferred
for the mass of air that the fan can move through the fins. (Note that the
volume of the air changes as it heats up, so mass is used in the calculations
instead of volume.)
And yes, in a counterflow situation (i.e. heat flowing through the fins in
a direction opposite to the flow of air), the coolest air contacts the coolest
portion of the fins, and the hotest air contacts the hotest part of the fins.
Since the highest heat transfer occurs where the temperature difference is
greatest, one might think that the greatest heat transfer would occur for
parallel flow situation. But no, it's the opposite when one does the calculus.
The reason is that the heat transfer in the counterflow situation works over
a longer period of time since the temperatures of the 2 media (i.e. fins and
air) remain different throughout the time of transit. In the parallel flow
situation, the greatest transfer occurs at the beginning when the 2 media
have the greatest temperature difference, but the temperature difference
falls of rapidly as the air flows toward the cooler part of the fins and the
heat transfer falls off as well.
For overclocking, where adequate cooling becomes vital, I'd go with
water cooling for the CPU. That would leave more room inside the case
for air cooling of the other components. But... that's an added expense
that one may not want to bear.
*TimDaniels*
TheGlimmerMan
Aug 19, 2012, 4:05:25 PM8/19/12
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On Sun, 19 Aug 2012 14:34:23 -0400, "k...@att.bizzzzzzzzzzzz"
<k...@att.bizzzzzzzzzzzz> wrote:
>
>Or DimBulb. It's sometimes hard to tell them apart.
You and Larkin are both idiots.
<k...@att.bizzzzzzzzzzzz> wrote:
>
>Or DimBulb. It's sometimes hard to tell them apart.
k...@att.bizzzzzzzzzzzz
Aug 19, 2012, 9:11:22 PM8/19/12
to
Quadibloc
Aug 20, 2012, 1:16:15 AM8/20/12
to
On Aug 18, 11:17 pm, Jeff Liebermann <je...@cruzio.com> wrote:
> What you want is immersion cooling:
I did a Google search after my post, and found that all the references
> What you want is immersion cooling:
to the use of mineral oil were to immersion cooling. However, I have
also seen it noted that mineral oil could damage some parts of present-
day computers.
I was thinking in terms of avoiding immersion, but using a forced
flow.
John Savard
Jasen Betts
Aug 20, 2012, 2:38:52 AM8/20/12
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driven by a 1200W series universal motor (Electrolux :-) ) The universal motor
made it more obvious because these motors respond more to load changes.
Modern cooling fans often have a pulse output that indicates fan speed, but
monitoring software seems to only alarm on a low speed, where a high speed
should possibly also be alerted as it may indicate a clogged heatsink.
The fans with a PWM input would be harder to handle as the pwm to
speed relationship would need to be compared
--
⚂⚃ 100% natural
--- Posted via news://freenews.netfront.net/ - Complaints to ne...@netfront.net ---
David
Aug 20, 2012, 6:43:35 AM8/20/12
to
On Sat, 18 Aug 2012 17:54:54 -0700, Quadibloc wrote:
> On Aug 18, 11:19 am, "Skybuck Flying" <Windows7I...@DreamPC2006.com>
> wrote:
>
>> Place the heatsink fins 90 degrees turned so that the overflow must go
>> OVER the heatsink fins and not in between.
>
All of you are responding to a known troll and idiot, Skyduck Farting.
> On Aug 18, 11:19 am, "Skybuck Flying" <Windows7I...@DreamPC2006.com>
> wrote:
>
>> Place the heatsink fins 90 degrees turned so that the overflow must go
>> OVER the heatsink fins and not in between.
>
All of you are responding to a known troll and idiot, Skyduck Farting.
John Larkin
Aug 20, 2012, 12:48:33 PM8/20/12
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cooling at zero flow.
>so there is a definite bias towards not blocking off half the free air
>flow. I would guess at something more like allowing 2/3 to 3/4 of free
>airflow as about the best depending on the exact heatsink geometry. It
>could easily be higher - easy enough to do the experiment.
vary the airflow resistance, like the pin or fin density or something,
and keep the remaining geometry the same.
This would matter in a case like deciding between two heatsinks that
are the same overall dimensions but have different fin densities,
cooled by the same fan. Heatsink data sheets give you half the
information you need (theta vs flow) but not the other half
(backpressure vs flow).
>
>I suspect the perfect shape for an optimum heatsink is rather more
>complex than the typical fins we get but the designs used at present are
>good enough and much easier to engineer. Heat pipes have helped
>enormously with the latest generation of quiet heatsinks.
>
>It is a sobering thought that high performance CPUs often have a heat
>output per unit area that exceeds the tip of a soldering iron.
putting the hottest bits into the corners or something.
Flasherly
Aug 20, 2012, 1:59:07 PM8/20/12
to
On Aug 20, 12:48 pm, John Larkin
ostensibly to remove added abstractions through dynamic modeling
practices as gate clocking and fetch latches contingent upon sensor
relays. Labeled under a safety badge to ensure another preventative
layer against failure conditions, the intent is established in
advantage to saving the core processor when a $2 heatsink or fan
malfunctions or improperly is manipulated outside provisional intents
by which they're packaged and distributed.
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>
> I wonder if CPU chip layouts include hot-spot distribution, like
> putting the hottest bits into the corners or something.
I wouldn't as generally implemented within a more direct approach
>
> I wonder if CPU chip layouts include hot-spot distribution, like
> putting the hottest bits into the corners or something.
ostensibly to remove added abstractions through dynamic modeling
practices as gate clocking and fetch latches contingent upon sensor
relays. Labeled under a safety badge to ensure another preventative
layer against failure conditions, the intent is established in
advantage to saving the core processor when a $2 heatsink or fan
malfunctions or improperly is manipulated outside provisional intents
by which they're packaged and distributed.
John Larkin
Aug 20, 2012, 5:28:52 PM8/20/12
to
Flasherly
Aug 20, 2012, 7:14:40 PM8/20/12
to
On Aug 20, 5:28 pm, John Larkin
attributed heat as randomness to an ordering of chip density cannot
either wrong or right, whether suspect or implicit in indulgence, much
as application [more correctly] negates relevancy by dint of simple
apparency;- well, almost. . .I did elect not to turn on heat
throttling in my CMOS.
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>
> Word salad. You must be AlwaysWrong.
Lex parsimoniae -- irrespective of older processors I do own, to have
>
> Word salad. You must be AlwaysWrong.
attributed heat as randomness to an ordering of chip density cannot
either wrong or right, whether suspect or implicit in indulgence, much
as application [more correctly] negates relevancy by dint of simple
apparency;- well, almost. . .I did elect not to turn on heat
throttling in my CMOS.
Skybuck Flying
Aug 20, 2012, 9:12:06 PM8/20/12
to
"Jeff Liebermann" wrote in message
news:g3s0381vglrf8hrn5...@4ax.com...
On Sat, 18 Aug 2012 12:59:41 -0700, John Larkin
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>I have this theory that the fins of a heat sink should reduce a fan's
>free-flow rate by 50% for optimum heat transfer.
"
>I have this theory that the fins of a heat sink should reduce a fan's
>free-flow rate by 50% for optimum heat transfer.
"
On the original assertion, that it's better to suck than to blow,
methinks that's wrong.
"
I will draw a more detailed drawing for you what I ment with "suck". There
methinks that's wrong.
"
is also some "blow" involved.
Side view of proposed heat sink design by skybuck:
+--------------------------------------+
<out----------- airflow -------------in FAN or CASE FAN
<------------- airflow ---------------
|^|^|^|^|^|^|^|^|^|^|^|^| <- suckage effect going up
|S|S|S|S|S|S|S|S|S|S|S|S|
|U|U|U|U|U|U|U|U|U|U|U|U| <- heatfins
|C|C|C|C|C|C|C|C|C|C|C|C|
|K|K|K|K|K|K|K|K|K|K|K|K|K|
+--------------------------------------+
By blowing air over the heat fins as proposed this will hopefully create a
suck effect, sucking any dust out from between the heatfins
I do see some problems with this design... the tunnel will be small.... and
a big fan will have trouble blowing air into it... maybe a small one will be
enough... low rpm hopefully.
Bye,
Skybuck.
Skybuck Flying
Aug 20, 2012, 9:16:40 PM8/20/12
to
"Timothy Daniels" wrote in message
news:tfKdnTtI9v-qFK3N...@earthlink.com...
"Jeff Liebermann" wrote:
> [.............] On the original assertion, that it's better to suck than
> to blow,
> methinks that's wrong. .....
"
Given the same mass/sec flow of air over the fins of a heatsink,
the best heat transfer is by blowing due to the greater turbulence -
which disturbs the boundary layer of air that lies in contact with
the fins and puts more flowing air in direct contact with the surface
of the fins. In the case where the fins rise up away from the source
of the heat, it's best to blow downward from the ends of the fins
toward the source of the heat. IOW, the air should move in a
direction opposite to the heat flow.
This principle is not only used in heat transfer systems, but also in
biological systems in oxygen transfer through membranes - as in
fish gills where the blood moves across the gill membrane in a
direction opposite to the flow of water. The basis of this principle
lies in the finite heat (or gas) capacity of a fluid and that greatest
heat (or gas) flow occurs as a linear function of the difference of
temperature (or gas concentration) between 2 bodies. Apply a little
calculus, and the principle of opposing flows results. This design
principle was recently seen when I opened up the case of a friend's
PC to clean it out: The cooling fins for the CPU rose up from the CPU,
and the cooling fan blew air down along the fins toward the CPU.
Obviously, the designer had paid attention during college freshman
physics.
"
I'd love to see simulation that actually includes dust particles and hair to
see how much effectiveness remains for this theory.
I suspect the simulation software used at the time did not include these
factors, and therefore all designs might be totally wrong for dusty/hairy
environments.
Bye,
Skybuck.
Skybuck Flying
Aug 20, 2012, 9:19:55 PM8/20/12
to
wrote in message news:7h81381lnr5h0k3sd...@4ax.com...
On Sun, 19 Aug 2012 01:56:38 -0500, "Tim Williams"
<tmor...@charter.net> wrote:
>Note that heat transfer by volume isn't usually the goal, so much as
>minimum temperature is. In a counterflow setup, the hottest part of the
>heatsink is cooled by the hottest air. If you flip it around, the hottest
>part of the heatsink gets cooled by the coolest air, achieving the highest
>heat flux for a given surface area and temperature difference -- more
>power density, at some expense to mass flow and pumping loss. You might
>avoid this, for example, if you had to use pure nitrogen (or helium, for
>that matter) for some process, minimizing the gas flow to keep operating
>cost down.
"
compressor to compress the air to a few bars, the air gets quite hot,
then let it go through a heat exchanger to get rid of most of the heat
and cool the pressurized air closer to ambient temperature.
Let the air expand to normal ambient pressure and the air temperature
is now well below ambient temperature and let it flow through
semiconductor heatsinks to the environment.
To avoid problems with dust and condensation, a closed loop might make
sense, but of course, now the heat exchanger would also have to
dissipate the heat from the semiconductor. However, the heat exchanger
can be remotely located and it can have much higher temperatures than
the semiconductors, getting rid of the heat into the environment would
be easier.
"
I like this idea of a closed air system very much...
Maybe a case which is build entirely out of "heatsinks" or something... to
get rid of as much heat from inside the case to the outside...
without actually sucking in any dust/hair.
Bye,
Skybuck.
John Larkin
Aug 20, 2012, 9:24:05 PM8/20/12
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On Tue, 21 Aug 2012 03:19:55 +0200, "Skybuck Flying"
It's been done, with better working fluids. You have one in your
kitchen.
kitchen.
Martin Brown
Aug 21, 2012, 3:04:59 AM8/21/12
to
thing is made of shiny metal. Proportional to flow plus a small additive
constant isn't exactly rocket science. In any forced air cooling design
worth its salt airflow cooling totally dominates.
>> so there is a definite bias towards not blocking off half the free air
>> flow. I would guess at something more like allowing 2/3 to 3/4 of free
>> airflow as about the best depending on the exact heatsink geometry. It
>> could easily be higher - easy enough to do the experiment.
>
> I don't think the experiment is easy. With the same fan, you'd have to
> vary the airflow resistance, like the pin or fin density or something,
> and keep the remaining geometry the same.
on moving the air through it and to first order the output velocity
field scales fairly well apart from deep inside the heatsink where there
is or should be some turbulence.
It occurs to me in this discussion that the performance of a standard
rectangular vaned heatsink might be improved by putting diagonal wires
through the vanes at say 45 degrees to generate vortex wakes that mix up
the laminar flow after the first or second set of vanes.
> This would matter in a case like deciding between two heatsinks that
> are the same overall dimensions but have different fin densities,
> cooled by the same fan. Heatsink data sheets give you half the
> information you need (theta vs flow) but not the other half
> (backpressure vs flow).
proxy for back pressure and many PC fans are so equipped.
>> I suspect the perfect shape for an optimum heatsink is rather more
>> complex than the typical fins we get but the designs used at present are
>> good enough and much easier to engineer. Heat pipes have helped
>> enormously with the latest generation of quiet heatsinks.
>>
>> It is a sobering thought that high performance CPUs often have a heat
>> output per unit area that exceeds the tip of a soldering iron.
>
> I wonder if CPU chip layouts include hot-spot distribution, like
> putting the hottest bits into the corners or something.
drive buffers are probably physically close to the edge of the die.
Regards,
Martin Brown
Skybuck Flying
Aug 20, 2012, 10:22:28 PM8/20/12
to
Also perhaps a vaccuum would be created on the suck sections.
So then on the bottom little holes would need to be made to create little
openings to let air in...
So then it starts to seems a little bit more like the blown through
design... but this would be
some kind of hybrid design.
Some blow through and some suckage ;) :)
Hopefully dust won't be sucked in from those tiny little holes... or at
least a whole lot less then the other designs...
otherwise it would be pointless.
Bye,
Skybuck.
So then on the bottom little holes would need to be made to create little
openings to let air in...
So then it starts to seems a little bit more like the blown through
design... but this would be
some kind of hybrid design.
Some blow through and some suckage ;) :)
Hopefully dust won't be sucked in from those tiny little holes... or at
least a whole lot less then the other designs...
otherwise it would be pointless.
Bye,
Skybuck.
Skybuck Flying
Aug 20, 2012, 10:37:05 PM8/20/12
to
"John Larkin" wrote in message
news:vno538h4q8l7r2jlc...@4ax.com...
simply be a mini/tiny refrigator and place the entire pc inside of it...
My fridge actually has small little holes on the back side... so some cables
could go through it...
But it's a scary idea... electronics and moist.... hmm I'll have to look
into this somemore...
For now biggest drawback could be noise of fridge.... or maybe fridge can't
handle the pc heat at all...
Hmm..
Bye,
Skybuck.
Skybuck Flying
Aug 20, 2012, 10:31:16 PM8/20/12
to
Well, if this is the case, if it's the case of maximizing contact area then
here is an idea for a chip/gpu:
The gpu is cut up into many tiny little pieces.
The tiny little pieces are distributed over the entire graphics card.
Tiny little heatsinks which are larger then the gpu piece are stuck on top
of it.
This should maximize the area a bit more... better distribution of heat.
Since it's a parallel chip consisting out of multiple cores... it should be
possible to cut up those cores and distribute them
across the graphics card...
Added benefit is also more lanes towards all tiny little cores... for more
bandwidth and more memory lookup power.
These tiny little gpu pieces could by stuck between capcitators... or maybe
even on top of them... or vice versa...
Not sure if that's a good idea... or where to best place them... but some
spreading out seems nice.
If this would be any better than current situation remains to be seen...
current heatsinks also pretty massive
across the graphics board... so maybe it don't matter, or just very
little...
Or maybe it does matter... maybe having everything on a small little area
prevents optimal heat transfer...
Thus cutting the chip up into multiple pieces might make it better.
Maybe the entire chip design should be more like a building with windows in
it... and blow air directly through the chip... instead of an additional
heatsink.
Bye,
Skybuck.
here is an idea for a chip/gpu:
The gpu is cut up into many tiny little pieces.
The tiny little pieces are distributed over the entire graphics card.
Tiny little heatsinks which are larger then the gpu piece are stuck on top
of it.
This should maximize the area a bit more... better distribution of heat.
Since it's a parallel chip consisting out of multiple cores... it should be
possible to cut up those cores and distribute them
across the graphics card...
Added benefit is also more lanes towards all tiny little cores... for more
bandwidth and more memory lookup power.
These tiny little gpu pieces could by stuck between capcitators... or maybe
even on top of them... or vice versa...
Not sure if that's a good idea... or where to best place them... but some
spreading out seems nice.
If this would be any better than current situation remains to be seen...
current heatsinks also pretty massive
across the graphics board... so maybe it don't matter, or just very
little...
Or maybe it does matter... maybe having everything on a small little area
prevents optimal heat transfer...
Thus cutting the chip up into multiple pieces might make it better.
Maybe the entire chip design should be more like a building with windows in
it... and blow air directly through the chip... instead of an additional
heatsink.
Bye,
Skybuck.
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