More info on intermittent boot PC failure

I left a message month or so back about a problem I was/am having with
one of my computers. After being on for a while (I normally leave my
computers on, this particular one started this behavior couple months
ago), the computer will basically stop working. As in, the light will
still be on and the screen blank, but nothing will bring it back.
Rebooting doesn't work; not beeps; no nothing, except the PSU fan being
on. I received some advice from some of you, one of which was from Kony
saying to test the PSU with multi-meter. Haven't gotten my hands on one
of those yet and I've been leaving the computer off most of the time now
until I can devote some time to figuring out the problem.

However, recently it was on and we had a "power-flick" which lasted long
enough to reboot the computers. Well, this 'finicky' one didn't boot
back up, exhibiting the same behavior as before. So I unplugged it,
opened it up, looked around again, didn't see anything (CPU not loose,
capacitor caps look OK, everything plugged in tight, etc), so I plugged
everything back up and it worked. Then it happened again a couple days
later, and it wouldn't boot back up, same thing. So I decided to try just
unplugging the AC power cord to the PSU for a minute, then plugging it
back in and seeing what would happen. It worked. So it seems that
cutting it off from any power for a bit of time seems to reset it enough
to make it work.

So. Does this sound like a CMOS thing or a PSU thing or something else
anyone can think of off the top of their head? I'm only asking to see
if anyone has noticed this before. Not assuming (or looking for)
that someone will diagnose the problem over the net. Only checking for
similar behavior and any guidance in the right direction.


Thanks,
jab3

On Thu, 22 Sep 2005 10:38:39 -0500, jab3 <jab3@nowhere.mg>
wrote:

>I left a message month or so back about a problem I was/am having with
>one of my computers. After being on for a while (I normally leave my
>computers on, this particular one started this behavior couple months
>ago), the computer will basically stop working. As in, the light will
>still be on and the screen blank, but nothing will bring it back.
>Rebooting doesn't work; not beeps; no nothing, except the PSU fan being
>on. I received some advice from some of you, one of which was from Kony
>saying to test the PSU with multi-meter. Haven't gotten my hands on one
>of those yet and I've been leaving the computer off most of the time now
>until I can devote some time to figuring out the problem.
>
>However, recently it was on and we had a "power-flick" which lasted long
>enough to reboot the computers. Well, this 'finicky' one didn't boot
>back up, exhibiting the same behavior as before. So I unplugged it,
>opened it up, looked around again, didn't see anything (CPU not loose,
>capacitor caps look OK, everything plugged in tight, etc), so I plugged
>everything back up and it worked. Then it happened again a couple days
>later, and it wouldn't boot back up, same thing. So I decided to try just
>unplugging the AC power cord to the PSU for a minute, then plugging it
>back in and seeing what would happen. It worked. So it seems that
>cutting it off from any power for a bit of time seems to reset it enough
>to make it work.
>
>So. Does this sound like a CMOS thing or a PSU thing or something else
>anyone can think of off the top of their head? I'm only asking to see
>if anyone has noticed this before. Not assuming (or looking for)
>that someone will diagnose the problem over the net. Only checking for
>similar behavior and any guidance in the right direction.
>


Most likely the power supply. Can't think of anything else
it would be offhand, but there might be a lesser chance it's
something else instead. You might strip the system down to
bare essentials, underclock it if possible, and disconnect
anything that might use 5VSB, for example a network card,
PS2 or USB devices, and then try to recreate these failure
scenarios. If it then still does this, odds start swaying
towards the motherboard. Sometimes motherboards do have
flaws in waking up from power management modes and you might
see if your board manufacturer has any bios notes that would
seem to address a related issue. I'd still scutinize the
power supply first and last, though.