No POST; take a guess

[yaugin]

One of desktops is on its last leg and it's not worth fixing up
anymore. In total, I had to make 3 major repairs over the course of 5
years, by far the worst record for any PC I've owned. I'll actually be
glad to use this as an excuse to splurge on a new build, but it makes
me nervous to trust any of the brands involved again (though, not a
problem anymore for abit).

The most recent issue? Well, first, I experienced a hard lock. Hit the
reset button and it recovered ok. A week later, I got a random
restart, but rebooted fine. And finally, a week after that, I got a
lockup in Firefox. Rest of the computer seemed ok until I tried to
force a reboot, then it was a total lockup. Hit the reset button, and
the PC hasn't posted since, at all (no beep code). The instability was
uncharacteristic as it had been running flawlessly for about a year
since the last repair (had to swap out the video card due to a spider
having crawled through the hole in the back of the molex connector,
and made a mess of itself upon contacting the exposed metal inside...
imagine my disbelief when I discovered this after hours of the usual
troubleshooting).

Specs:
Abit NF7-S2 Socket A motherboard
Athlon XP 2100+
2x512mb DDR Corsair memory
Radeon 9800 Pro AGP
Thermaltake Purepower 500w

So far I have tested a different PSU (Antec Neopower 500w), no luck.
Also tried an extra CPU I had laying around (Duron 800mhz), but it's
been out of commission so long I'm honestly not sure if it still
works. All the capacitors look ok. I'm leaning towards a dead
motherboard, but I've never actually seen a computer die in the middle
of normal operation like that -- previously whenever I had a part die
it was because of a power supply exploding, or my elderly father
trying to install PCI cards with the power on... (grr) or some dumb
arachnid crawling into places where he shouldn't be... anyway if you
have a good guess let me know before I charge up a few hundred bucks
at NewEgg.

 

[Dave]

One of desktops is on its last leg and it's not worth fixing up
anymore. In total, I had to make 3 major repairs over the course of 5
years, by far the worst record for any PC I've owned. I'll actually be
glad to use this as an excuse to splurge on a new build, but it makes
me nervous to trust any of the brands involved again (though, not a
problem anymore for abit).

The most recent issue? Well, first, I experienced a hard lock. Hit the
reset button and it recovered ok. A week later, I got a random
restart, but rebooted fine. And finally, a week after that, I got a
lockup in Firefox. Rest of the computer seemed ok until I tried to
force a reboot, then it was a total lockup. Hit the reset button, and
the PC hasn't posted since, at all (no beep code).

(snip)

Wow, I had a SMC brand wireless adapter causing those exact symptoms on a
high-end homebuilt computer my wife uses. I've seen other network adapters
cause similar symptoms. But the no POST and no beep code? I think you
might have symptoms of more than one problem.

I'd suggest that you throw away the Thermaltake Purepower 500W power supply.
Most likely explanation for your original symptoms was a bad power supply.
Only problem is, a bad power supply can take down other components when it
dies. Coincidentally (or maybe not?) the last system I saw with truly
****ed hardware components (beyond the normal failures, that is) was a 500W
Thermaltake brand power supply that died in a rather spectacular manner (4th
of July!) and took the mainboard, CPU and a hard drive down with it.

Is there anything wrong with your purepower 500W? Maybe, maybe not. But
you are going to be building from scratch, so you will need (not optional) a
brand new power supply anyway. You could measure the DC outputs of the
purepower 500, but that would only tell you if the voltages are stable at
that particular instant. It's not worth a chance, toss that puppy.

As for the rest of the system, I would suggest you try a THIRD power supply
before you give up on it. A known good power supply in one system might not
necessarily allow another good system to POST. Your symptoms are still
pointing to a bad power supply. But then, the CPU isn't getting the voltage
it needs to POST, and while the power supply is most likely suspect (by
far), there are less common causes. You could also try resetting CMOS data
a few times, but that is a long-shot. If a THIRD power supply, and
resetting CMOS data doesn't work, you are definitely looking at a bad
motherboard. It could also be a bad CPU, but the odds on that are like 1 in
a million. Given your symptoms, following the odds, it boils down to power
supply (96%), motherboard (2%), CPU (HALF a percent, if that) and the other
1.5% is anybody's guess. Anything can cause anything, but if you follow the
symptoms, you usually find the problem right away. The SYMPTOMS are
pointing directly at the power supply. Even though you say you've already
replaced it.

There's not a lot you can do that you haven't already done. Time to start
over, probably. -Dave