Memory confusion - P5WD2
DCIFRTHS
The chipset on this motherboard officially supports DDR2 667 as the fastest
memory. Asus describes this motherboard as natively supporting DDR2 800. Can
someone explain, if the memory controller supports up to 667, how the board
natively supports the 800 speed?
Additionally, if I plug in a DDR2 800 module that has the SPD set at 2.1V
with timings of 4-4-4-12, will the board recognize this module, and
overclock the memory bus to run it at those speeds, or will run it at slower
speed by default?
Thanks for any insight to this situation!
Paul
wrote:
From the manual:
*******
DRAM Frequency [Auto]
Allows you to set the DDR operating frequency.
Configuration options: [Auto] [DDR2-400MHz] [DDR2-533MHz]
[DDR2-667MHz] [DDR2-800MHz] [DDR2-711MHz] [DDR2-889MHz]
[DDR2-1067MHz]
Available DRAM frequency options in various FSB settings
FSB Configuration options
Auto DDR2- DDR2- DDR2- DDR2- DDR2- DDR2- DDR2-
400 533 667 711* 800* 889* 1067*
FSB 1066 € € € € € € € €
FSB 800 € € € € €
FSB 533 € € €
* Provided for overclocking purpose only.
*******
The SPD EEPROM chip on a DIMM, is only supposed to be programmed
with JEDEC approved information. This aids compatibility, in
that a BIOS only need know how to parse the expected JEDEC
values. I cannot find a reference to what JEDEC currently
approves, and if the max is still DDR2-667, then that is all
you should be finding programmed into the SPD.
AFAIK, for overclockable modules, it is up to the user to set the
parameters to reach the maximum value. After all, you want the
computer to be able to POST first, and then try overclocking it.
If the computer failed to POST, because of some problem running
at DDR2-800, you'd be pissed.
Paul
DCIFRTHS
The information you provided to me confirms my original posting. Anything
above DDR 667 is considered overclocking.
The modules in question are Crucial Ballistix modules. The specs are here
http://www.crucial.com/store/partspecs.Asp?IMODULE=BL2KIT12864AA804
I specifically asked Crucial what the SPD was programmed to, and they
insisted (more than one rep confirmed this) that it was set to the timings
listed in the link above (4-4-4-12). This seems rather strange to me. If
anyone is using Ballistix modules and can confirm the part number they have,
and what the SPD is programmed to, I would greatly appreciate it.
I also searched for the standard JEDEC timings, but couldn't find them.
Kingston and Corsair have some information, but they seem to differ on what
the standard is. I am total agreement that the SPD should be set to JEDEC
standards.
"Paul" <nos...@needed.com> wrote in message
news:nospam-2210...@192.168.1.178...
> FSB 1066 ? ? ? ? ? ? ? ?
> FSB 800 ? ? ? ? ?
> FSB 533 ? ? ?
DCIFRTHS
for DDR2. They said it only specifies the voltage and frequency (MHz).
Anyone know if this is true?
"Paul" <nos...@needed.com> wrote in message
news:nospam-2210...@192.168.1.178...
> FSB 1066 ? ? ? ? ? ? ? ?
> FSB 800 ? ? ? ? ?
> FSB 533 ? ? ?
Paul
<DCIF...@nowhere.com> wrote:
> Paul,
>
> The information you provided to me confirms my original posting. Anything
> above DDR 667 is considered overclocking.
>
> The modules in question are Crucial Ballistix modules. The specs are here
> http://www.crucial.com/store/partspecs.Asp?IMODULE=BL2KIT12864AA804
>
> I specifically asked Crucial what the SPD was programmed to, and they
> insisted (more than one rep confirmed this) that it was set to the timings
> listed in the link above (4-4-4-12). This seems rather strange to me. If
> anyone is using Ballistix modules and can confirm the part number they have,
> and what the SPD is programmed to, I would greatly appreciate it.
>
> I also searched for the standard JEDEC timings, but couldn't find them.
> Kingston and Corsair have some information, but they seem to differ on what
> the standard is. I am total agreement that the SPD should be set to JEDEC
> standards.
I don't think this document is going to help matters - I was really
surprised to find that JEDEC has put this in the free download
catagory. PDF page 74 has some classifications for the memory -
800's come in 4's, 5's, and 6's , 667's in 4's and 5's, both 400's
and 533's come in 3's and 4's.
http://www.jedec.org/download/search/JESD79-2B.pdf
I had to register to use the search engine, but if you are lucky,
the document will download for you without further hassle.
Now, let's review the situation on your motherboard again. Say
that JEDEC is actually allowing DDR2-800, according to that Jan. 2005
document above. In the BIOS, Asus can still consider the use of the
divider that gives DDR2-800, to be non-standard, which means even
if the top timing in the SPD is for DDR2-800, the BIOS is still under
no obligation to go there immediately. I just looked in the Intel
955X chipset datasheet, and DDR2-667 is considered to be the top speed.
That could mean, that the dividers used to get the higher memory
clocks are undocumented or unsupported by Intel. (I didn't read
the whole doc. My past experience is, Intel is not completely
honest about what dividers are available.)
PDF page 20 has a strange statement. And there is no elaboration
later. It says DDR2-667 4-4-4 is not supported ? I wonder what
the hell that means. They don't make datasheets the way they
used to...
http://download.intel.com/design/chipsets/datashts/30682801.pdf
I looked in the Crucial FAQ database and found this:
http://www.crucial.com/kb/answer.asp?qid=4050
"The specs for your DDR2 Ballistix products have two values
listed. One is a "validated" value, while the other is an "SPD"
value. Why are these different?
The memory timings listed as the validated values are the timings
that we actually test our Ballistix products to. The timings
listed as SPD settings are the values that are programmed into
the module's SPD. Your system's BIOS will often use these values
as the default for your memory settings.
The timing values in the SPD are not set as aggressively as the
ones used in our test flow because many systems are not capable
of running at these tighter timing settings. By programming less
aggressive values into the SPD, we are able to maximize the
number of platforms that DDR2 Ballistix products will work with
right out of the box.
To operate at the published validated timing specifications, you
may need to manually set these parameters in your BIOS. Consult
your motherboard manufacturer's documentation for detailed
information on how to change these settings."
They said it better than I could :-)
Paul
DCIFRTHS
I am registered at JEDEC, but I obviously missed this document. Nice find.
So at least DDR2 800 is a standard!
The Crucial FAQ directly contradicts what the reps I spoke to said. I am
also wondering how old the document is because it says that there are two
sets of timings listed for the Ballistix modules. Currently, there is only
one set of timings posted, on the site, for their current modules. I wonder
if they have changed their thinking on programming the SPD? Any Ballistix
owners out there?
You are correct regarding the chipset. It officially supports up to DDR2
667. However, the Asus site claims "native" DDR2 800 support. See quote
below:
"Native DDR2 800 Support
To attain top performance, ASUS engineers successfully unleashed the true
potential of DDR2 memory. Native DDR2 800 maximizes system performance by
eliminating the bottleneck when overclocking both the CPU and memory,
providing great performance for 3D graphics and other memory demanding
applications."
Asus may be using the "unpublished" multipliers you spoke to.
Question: Will I be able to manually adjust the BIOS to run my modules to a
slower speed, let's say, DDR2 667?
"Paul" <nos...@needed.com> wrote in message
news:nospam-2310...@192.168.1.178...
Paul
wrote:
> Paul,
>
> I am registered at JEDEC, but I obviously missed this document. Nice find.
> So at least DDR2 800 is a standard!
>
> The Crucial FAQ directly contradicts what the reps I spoke to said. I am
> also wondering how old the document is because it says that there are two
> sets of timings listed for the Ballistix modules. Currently, there is only
> one set of timings posted, on the site, for their current modules. I wonder
> if they have changed their thinking on programming the SPD? Any Ballistix
> owners out there?
>
> You are correct regarding the chipset. It officially supports up to DDR2
> 667. However, the Asus site claims "native" DDR2 800 support. See quote
> below:
>
> "Native DDR2 800 Support
> To attain top performance, ASUS engineers successfully unleashed the true
> potential of DDR2 memory. Native DDR2 800 maximizes system performance by
> eliminating the bottleneck when overclocking both the CPU and memory,
> providing great performance for 3D graphics and other memory demanding
> applications."
>
> Asus may be using the "unpublished" multipliers you spoke to.
>
> Question: Will I be able to manually adjust the BIOS to run my modules to a
> slower speed, let's say, DDR2 667?
I downloaded a DDR2 datasheet from Micron (126 pages!) and the
clock period for the fastest chip ranges from 3ns to 8ns.
3ns is 333MHz input clock (DDR2-667 rate). 8ns is 125MHz, which
gives less than DDR2-400 rate, meaning that DDR2, like DDR, is
backward compatible with lower rates and downward-adjustable.