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Old February 10th 04, 12:50 PM
kony
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On Tue, 10 Feb 2004 09:18:56 +0000 (UTC), "Nick G" ignore @ nospam.com
wrote:

The following problem has confounded every IT friend and support person i
have presented it to and appears to defy logic so i am throwing it to a
broader audience of experts to see if it elicits some ideas. Thanks in
advance for considering it and apologies for cross-group posting!

Problem: Spontaneous power-offs that take place between 15 seconds and 30
minutes after booting. As if the power cord was yanked out of the back.
Green M/B LED remains on, power cord has to be disconnected for several
seconds before re-boot can take place.


To clairify, every time it powers off, you MUST disconnect AC cord (or
flip PSU rear switch) to get it working again, you can't just wait a few,
say 3 minutes, and it'll come on again?



PC background: home-built 18 months ago, ran fine until last week. I have
been building PCs for 15 years and have spent the last week running through
every permutation of test i can think of, to no avail.

Components tested (all of which have, in every configuration, replicated the
problem):

M/B
Asus a7v333 latest bios
Asus a7v8x-x v06 bios - rejects flash to latest 08 bios
temp problem? No. M/B temp under 35 degrees c at time of power-down (have
been staring at PC probe's temp montitor as it has gone down on 2 occasions.
Immediate boot-ups after power-down reveal no discrepancies in bios-based
temp monitor i.e. also reports 35 degrees c or under)


You switched boards, so for the time being we can assume it's not the
board, but what about the OS install? Did you do a clean install, or is
it possible there's a virus jumping from drive to drive, or residing on
another system on a LAN?


CPU
AMD Athlon 2100+
AMD Athlon 2500+
temp problem? No CPU temp under 40 degrees c at time of power-down (have
been staring at PC probe's temp montitor as it has gone down on 2 occasions.
Immediate boot-ups after power-down reveal no discrepancies in bios-based
temp monitor i.e. also reports 40 degrees c or under). Bios-based
auto-shutdown set at 95 degrees c


What about the CPU heatsink? Is it one known to have problems, like those
TMD fans that were prone to short out? Even if another type of fan, I'd
try switching the CPU heatsink fan if you hadn't done so already.

HD
8GB Seagate- freshly fdisked/formatted but fails to complete winXp install
(lasts between 15mins and 25 mins) before powering off


OK, that rules out the virus possibility, assuming you were not always
booting from one of the HDDs or an infected floppy, CDR, etc, before
trying to install the OS.

In theory, a virus could be attached to a motherboard BIOS, but
realistically, it would have to be a very specific targeted, engineered
attack... not a reasonable consideration for a system that still posts,
boots, and anyone with the skill to do it, could find far better ways to
spend their time destructively if that was their goal... a BIOS virus is
just not likely enough to be worth considering.

20GB IBM- Win98SE - exhibits power-down symptoms every time, works fine on
other machines. Lasts the longest time, up to 30 mins, running in 640x480
res
80GB Maxtor - Win Xp Home - lasts the shortest time, rarely more than 15
minutes, power-offs can happen without any apps running but tends to happen
within a few seconds of 3Dmark03 running and within 15 minutes of Norton
AV2K4 running
Software problem? No. problem replicated with winxp install on fresh disk.
Also run each HD in isolation to others, i.e. with no other no HD IDE/power
connections

Graphics
Radeon 9800pro - exhibits power-down symptoms every time, works fine on
other machines
Radeon 9700 Pro exhibits power-down symptoms every time, works fine on other
machines
GeForce Ti4600 - exhibits power-down symptoms every time, works fine on
other machines
Graphics card problem? maybe, but three different cards have replicated the
problem. Run with default VGA drivers and latest drivers


No, can't be a graphics can problem with all of 'em exhibiting the same
problem, though you probably should've tried a more modest, less power
hungry card, would isolate heat and power issues more.


Memory
512Mb PC2700 Apacer CL2.5
512MB PC3200 Infineon CL 2.5
Memory problem? maybe, replicated with both DIMMS though. Could it be a
voltage issue? everything set to default in bios and no voltage setting
tampered with at any stage.


"replicated with both" isn't specific.
Do you mean, you tried each DIMM separately, in each board? I'll assume
so.

PSU
300W unbranded, came with case


You should've never even hooked this one up to a system, especially not
with any of the above video cards. Any number of components could be
damaged because of this power supply. We can hope that didn't happen.

400W high quality, multi-fan


Not to be picky, but specific make/model is more useful than telling us,
"high quality, multi fan". For example, some people think Enermax is high
quality, but might not be adequate for the parts you've mentioned above,
due to insufficient 3V/5V rail capacity. I've even seen people claiming
that trashy power supplies, like Kingwin or Turbolink, were high quality.

You could be quite right, that your new 400W IS high quality, but if you
hadn't mentioned it, I'd have guessed the power supply was the most likely
culprit.

Power problem? Dont know. the brand new 400w PSU immediately replicated the
problem. Have tried 4 different power cords in two houses on 5 different
sockets (!). All replicated the problem.


Your voltage levels are good, checked with a voltage meter? A high 12V
rail can also indicate a problem with the 3V/5V rail that is still at
correct voltage reading.

Others:
case - generic, have tried running the pc out of the case without any case
jumper connections or any other connections other than PSU housing, using
screwdriver to boot.


You didn't happen to put the boards on anti-static bags? Some conduct
electricity.


CD, DVD, Floppy, Soundcard, USB expansion card, game card expansion, other
USB connections - taken out/disonnected (ide, power etc) but problem still
exists


So the above list, is meaning that you removed ALL cards, devices, etc,
that with only the HDD, video, and a single DIMM the system still powers
off?

I have even tried, once an app is running, diconnecting mouse, keyboard and
monitor (!!) with the problem still taking place.

I have effectively changed PC entirely with these tests and still get this
problem!


Makes me think about the CPU heatsink fan again.


One idea that was thrown out was a bios-residing virus. is there such a
thing (i cannot find mention of one anywhere let alone scanning or removal
methods)?


Not a realistic concern, but you could always set bios to disable the
antivirus safeguard, and reflash the same bios version as it already has
(or even an earlier version) since you reported that it wouldn't accept
the latest version... which it itself is a bit puzzling unless you hadn't
disabled the BIOS virus protection and/or related jumper (I "think" those
use a bios setting, it was older boards that had a jumper, but I'm not
certain of it).

Does anyone have any other ideas?


Any other household applicances, lights, etc, exhibiting strange
behaviour?