a8v deluxe: won't post/cmos error/losing bios settings?
idiotprogrammer
I have a big problem. My motherboard stopped posting--no beeps at all.
It says "Reboot and select proper boot device or insert boot media and
press a key."
It gave two signs: first, a cryptic cmos error message.
Second, the bios "forgot" that my hard drive on promise controller was
standalone IDE and not RAID. During bios, it would not be able to find
anything on Promise until I changed the settings back in bios to
standalone.
It happened suddenly after working all right for a few months. This is
for a machine I built myself.
Some symptoms which may or may not be related to this problem:
****whirring fan problem. the power supply man sometimes makes rhthmic
noises. However, it didn't seem to be happening immediately before the
post problem.
***usb wifi card failure. just before i had this problem, my usb wifi
totally stopped working. actually, it gradually stopped working an hour
or two before, then totally failed (even after rebooting).
**in hardware monitor in BIOS, I see that the POWER FAN SPEED value is
in RED. It hovers around 1679 RPM. The CPU temperature is 52C/126F and
the MB temperature is 29C/84F. CPU fan speed is 2848. However POWER
FAN SPEED is the only thing in red; is that normal?
I have a Zalman cpu cooler, so cpu should be ok.
I'm guessing that the problem is either power supply or (more likely)
CMOS. Does anyone else want to take a guess?
Although I have some experience working inside the PC, I have no
experience replacing CMOS or a power supply. If I lose my CMOS
settings, does that mean I need to upgrade my bios again? Can I assume
that all of these CMOS settings affect bios/motherboard and not my data
(I don't have any RAID).
I have three hard drives, 2 on the via controller, one on RAID.
Honestly I can't remember which one has my mbr, but in boot priority,
the only thing that shows up is HDD1 on the VIA controller. The fact
that neither of the other two hdd show up as an option on the boot
order menu also seems to be cause for concern.
I'd appreciate any advice.
Robert Nagle, idiotprogrammer
houston, texas
Paul
"idiotprogrammer" <idiotpr...@gmail.com> wrote:
The power supply fan sounds like it is acting up. It could be that
the bearing is wearing on it. Fans with ball bearings tend to
last longer than fans with sleeve bearings - and that is mainly
because the sleeve bearing fans have such poor tolerances. There
are some sealed sleeve bearing fans that are good (Panaflo), but
you won't find those in a power supply. If the power supply has
a warranty (like a store warranty where you bought it), swapping
it might be the best solution. While I've opened up one power supply
here and changed a fan, be aware that there are high voltage
capacitors inside the PSU, and just like a TV set, you can never
assume everything in there is safe to touch. (HV caps frequently
have bleeder resistors on them, to make them safe, but a repair
person never assumes that the bleeders are still functional, when
working in there.) The best policy is to stay the hell out of
there.
The power fan speed being in red is normal, because modern power
supplies use quite low RPMs for their fans, lower than the
motherboard is expecting. I have two motherboards here, that
register in red, and everything is working just fine.
As for your CMOS settings, and the BIOS, those are two separate
animals. The BIOS is stored in a flash memory. Flash memory
is non-volatile, and does not need electricity for the information
to stay in place. The information flashed in there, is good for
at least 10 years, and perhaps a lot longer. When you pull the
CMOS battery, the BIOS flash memory is unaffected. The next
time the computer POSTs, new default values will be written into
the CMOS RAM, so it gets re-initialized. You will then need to
add all your custom settings, to get things back the way they
were.
The CMOS settings are stored in a 256 byte memory in the Southbridge.
The memory type is a static RAM, with a reasonably low power
consumption. The CMOS RAM has two sources of power. There is
the +5VSB signal from the power supply. That signal is available
as long as the switch is ON, on the back of the computer. If you
switch OFF at the back, or you unplug the computer, then the
+5VSB is not available. At that point, the battery is called on to
maintain the settings. By means of two diodes, current only
flows out of the battery, when the computer is switched OFF or
unplugged.
If you switched OFF or unplugged the computer, and these symptoms
appeared, then it could be that the CMOS coin cell battery is
depleted. Those should really last for years under normal
circumstances. Leaving the clear CMOS jumper in the wrong
position could drain it. Occasionally, some kind of hardware
problem can drain it (like a standoff touching something on
the back of the motherboard). You can buy a replacement battery at
most stores that sell batteries. The CR2032 is pretty commonly
available.
If the computer was powered, and the +5VSB was present on the
motherboard, and the settings got lost, that would be more
serious. It would imply that perhaps recently, you cleared
the CMOS while the system was still powered, and burned the
dual diode running from the coin cell to the Southbridge.
So, you can start by pulling the coin cell and run down to
Radio Shack. (Unplug the computer and wait at least 60 seconds
before you do that.) The battery should read around 3V or so.
If it is flat, it might be less than 2V.
If replacing the battery, you still find that computer cannot
keep its settings, even if the switch is left in the ON position
on the back, then something must be damaged. Like the dual
diode. Good luck finding someone with the skills to find and
replace it.
Paul
idiotprogrammer
(You know, it's funny; this kind of information about replacing cmos
and power supplies is not easy to find).
I'll report back later.
rj