This problem has baffled everyone...

kony wrote:
On Wed, 11 Feb 2004 12:43:21 +1300, "~misfit~"
wrote:

Nick G wrote:
It was tested in two different properties in different parts of
London and on multiple mains sockets. I am writing this in one of
those properties and on a working laptop which is being mains
powered with no problems. The most bizarre thing about this problem
is that i have replaced every single major component at least once
if not twice and have still got the problem!

Including mobo? I still think you need to study the capacitors,
maybe test them.

... but he's tried two different motherboards

G Yeah, I missed that bit in this extensive thread. That's why I asked
"Including mobo?"
--
~misfit~

Nick G wrote:
i am currently using the brand new a7v8x and can see no bulging...

Yeah. Sorry Nick, I missed that bit. G I guess I should read fewer
newsgroups and read the ones I continue with more thouroughly.

Good luck with your interesting problem. A great opportunity to learn.
--
~misfit~

"~misfit~" wrote in message
news
Nick G wrote:
thanks. caps on both boards look fine. no leaks or discolouration.

No bulging either? Top or sides? Sometimes capacitors from three
years to about 18 months ago can fail but still look ok. Usually
they'll bulge though, not always. I've had this problem more than
once. It only takes one cap to cause problems.
--
~misfit~

"BigStan" wrote in message
...
He means bad capacitors. Sometimes they go south and cause
instability. Link here -

http://www.motherboardrepair.com/

"Nick G" ignore @ nospam.com wrote in message
...
Bad Caps.
Can you expand on this?
thks
n

"Nick G" ignore @ nospam.com wrote in message ...
The following problem has confounded every IT friend
and support person i have presented it to and appears
to defy logic

Spontaneous power-offs that take place between 15 seconds
and 30 minutes after booting.

home-built 18 months ago, ran fine until last week.
I have been building PCs for 15 years

Asus a7v333 latest bios
Asus a7v8x-x v06 bios - rejects flash to latest 08 bios

Radeon 9800pro - exhibits power-down symptoms every time
Radeon 9700 Pro exhibits power-down symptoms every time,
GeForce Ti4600 - exhibits power-down symptoms every time,

300W unbranded, came with case
400W high quality, multi-fan
the 400w PSU is made by Q-Tec and

What did you learn in your 15 years of building PCs?
You should have measured voltages, lightened the load
(not by swapping one power hog of a video card for
another), and tried a high quality power supply.

Those motherboards rely on +3.3V and +5V almost
exclusively, and combined with a high-power video card,
many power supplies just can't handle the load. It's
possible that your 300W was marginal but weakened as its
capacitors aged, and the Q-tec may have been inadequate
all along. Anyone with 15 years of experience building
PCs should have noticed instantly that the Q-tec was
crap by simply peeking through the vent holes and seeing
all the empty space and small heatsinks and transformer.
Borrow, buy, or steal a good supply, like an Antec
(AKA Channel Well, but only if its +3.3V is rated for
at least 20A and its +12V for at least 15A), Fortron
(many names, like Sparkle, Aopen), or something used
by a major computer manufacturer, except Dell (wires
mixed up, will destroy motherboard when plugged in).

CBFalconer wrote in message ...
Wild guess - something is putting spikes on a power line and
triggering a crow-bar shutdown. At least it fits the facts.

Not even with the Q-tec crap supply. Even it has an RF filter
that'll block almost all spikes.

Name one consumer grade ATX supply made in the past 10 years
with a crowbar circuit in it. All they have is shutdown,
and it doesn't trigger on spikes, except unintentionally.

Hi, I have had a look through this thread but no one seems to have
mentioned the CMOS battery.

I had a brand new motherboard that had these exact symptoms, I tried
everything but nothing made a difference not even buying a top of the
range 'PC power and cooling' power supply rated for huge servers.

I was so sure it was a power issue that I didn't bother checking the
CMOS battery, it was brand new motherboard so the battery had to be
fine...

Sure enough the battery was low (but not that low) and replacing it
cured the problem completely just like that.

It was a co-worker that suggested changing it BTW, I probably would
have never even checked it left to myself and would have probably sent
the board back.

It doesn't seem to be an uncommon problem either after asking people I
know, although most motherboards just forget their settings at every
boot rather than just re-setting randomly.

Best of luck with it,

-Jon

"Nick G" ignore @ nospam.com wrote in message ...
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.

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.


Hey, Jay here. There is one component of the computer that you did
not replace and has to be constant the whole time. Even if you take
the MB out of the case you still have to plug up the POWER SWITCH to
it. If the power switch is flaky then you can lose power suddenly,
reboot, and cause hard crashes. On just about all PSUs if you just
kill the power like that with a short in a wire you will either have
to unplug the cord or reset the PSU(hold down the power button while
flipping the switch on the back to the - sign). Try replacing the
whole CASE with a brand new Antec PSU and see what happens.

On 11 Feb 2004 14:55:49 -0800, (Jay Cousins) wrote:


Hey, Jay here. There is one component of the computer that you did
not replace and has to be constant the whole time. Even if you take
the MB out of the case you still have to plug up the POWER SWITCH to
it. If the power switch is flaky then you can lose power suddenly,
reboot, and cause hard crashes. On just about all PSUs if you just
kill the power like that with a short in a wire you will either have
to unplug the cord or reset the PSU(hold down the power button while
flipping the switch on the back to the - sign). Try replacing the
whole CASE with a brand new Antec PSU and see what happens.

It is not necessary to replace the case to test that, the power switch can
either be used to turn the system on, then immediately unplugged from the
pin header, or removed initially, before power-on, and the system powered
on by shorting the two power switch pins.

which i tried. running the mb out of the case entirely. definitely not the
switch. Have a new case and PSU arriving in the next few days...


"kony" wrote in message
...
On 11 Feb 2004 14:55:49 -0800, (Jay Cousins) wrote:


Hey, Jay here. There is one component of the computer that you did
not replace and has to be constant the whole time. Even if you take
the MB out of the case you still have to plug up the POWER SWITCH to
it. If the power switch is flaky then you can lose power suddenly,
reboot, and cause hard crashes. On just about all PSUs if you just
kill the power like that with a short in a wire you will either have
to unplug the cord or reset the PSU(hold down the power button while
flipping the switch on the back to the - sign). Try replacing the
whole CASE with a brand new Antec PSU and see what happens.

It is not necessary to replace the case to test that, the power switch can
either be used to turn the system on, then immediately unplugged from the
pin header, or removed initially, before power-on, and the system powered
on by shorting the two power switch pins.

Just a quick note to thank everyone that posted for their contributions.
Whilst I have yet to resolve my little conundrum, I believe you have pointed
me in the right direction (new PSU arriving shortly) and contributed
significantly to my understanding of current PC homebuiling techniques.
With gratitude,
Nick

So basically you've tried replacing or disconnecting everything but the MB,
right?

Chances are vanishingly remote that it's a BIOS virus but... have you tried flashing
to an Older bios since you can't flash to a newer bios?

Will the system reboot sitting in the BIOS screens?
If you have NO hard drive in the system, will the system POST, nag you about having
no OS, sit a while and then reboot?

Have you tried also disconnecting your case fans?
And are you using the same HS/fan for both CPUs?
Is the MB correctly grounded at the right points by the mounting screws?
Since you haven't, apparently, swapped motherboards.... yet, make sure there is
nothing between the back of the MB and the case. You might also consider pulling
the MB and booting it on a foam block

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.

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)

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

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

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.

PSU
300W unbranded, came with case
400W high quality, multi-fan
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.

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

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)?

Does anyone have any other ideas?

Any help very much appreciated

Nick
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