Hello,
Here's one for you hardware gurus.

I've got a PC that has behaved badly on and off; shuts off sporadically.
It's a problem that was occasional at first and has gotten worse as
time's gone by. After a lot of messing around I've convince myself that
it's a hardware problem. (There are absolutely no messages in software;
the logs just end suddenly. And I've swapped out everything except the
video card, a Radeon 7500 AGP, seems doubtful that's doing it, but I
suppose it's possible.) Troubles are, (a) the motherboards's out of
warranty, and (b) I really like the board otherwise, it's got the best
on-board sound hardware I've ever heard. (It's an Abit, with a
socket-462 AMD processor, if you wonder.) Yeah, I should've returned it,
but it's so much hassle when it's mail-order and home built - take
everything apart, take out the CPU and RAM, package it up, and lose the
use of the system for a month until they send you a new one.  So if the
problem is at all tolerable I live with it - foolish, but that's water
under the bridge.

The deal is that I've always assumed this was the ACPI malfunctioning;
when it shuts off it's hosed and you can't reboot it until you manually
shut off the power-supply switch for 10 seconds or so - I'd guess that
has to turn off the 5V standby power so something can be reset.  So I'd
like to just shut ACPI off, but it appears that the BIOS just won't let
you shut off this feature. (How obnoxious is that?  Is that some kind of
"Energy Star" certification requirement?) So I Googled for a while and
found some postings somewhere from someone who got the bright idea to
bypass the PS-ON signal in the ATX power supply connector, and hold it
low so the mobo can't turn the PS off.  As an experiment, I rigged a
power supply cable extender to a SPDT switch which would allow me to
either route the PS-ON signal normally or tie it to ground.  It's weird;
I can turn it on via that switch but the system won't boot, probably
because nothing tells the mobo that's what it's supposed to be doing. 
So I figured that if I did the bypass switch after the system was on, it
would bypass PS-ON, thereby preventing the sporadic shutoff.  That
doesn't appear to work, as it shut itself off while I had the signal
bypassed.  Now I wonder if they actually use the PWROK (AKA "Power
Good") signal for this ACPI garbage.  Or is it possible that PWROK
signal can also indicate some sort of sporadic problem with the power on
the board?  (Kind of like the "Check Engine" light on your car, which
can mean anything from "your gas cap's loose" to "your engine's about to
explode.")

Oh well.  I think this board's ready for the garbage, but if anyone has
any other suggestions, it would make for an interesting experiment.

Vaughn




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