Extremely intermittent crashing

I come to you looking for help world4ch.  I never would have before, but I have exhausted my sources.  My problem is such, when I am using my computer, at random intervals my system will lock up.  Majority of the time happens while playing World of Warcraft, however it has locked up during just plain windows usage.

This STARTED about a month and a half ago when I attempted to overclock 200mhz.  I set back down and still received the issue intermittently... could not find any hardware issues however.  I reformatted my system for good measure and it fixed the problem.  Until the last week when its been happening again. 

I reformatted the entire box last night, installed nothing but basic drivers.  4 minutes after I formatted and booted into windows, locked up.  No viruses, no spyware obviously.  OS has just been reloaded.  I've performed a processor burn test, which tests okay.  I've ran MemTest86 which shows okay.  I've ran video card tests on my diagnostic CD (I work at Best Buy service department...fixing computers :P) and the video card looks good.

What the fuck is it?  Its not software, and all the hardware I can think of testing is fine.

Stats:
CPU: AMD XP 2800+  Barton Core
Memory: 1gig (2x512) PC2700 memory.
Motherboard: AOpen AK77-8XN.
Graphics Card: PNY NVidia GeForce 6600GT 128mb AGP 8x.
Heat: Idle-118F 48C.  Full Load-125F 52C.

Anyone have any fucking clues?

PSU on the way out?

Sagging voltage can produce such results.  I'm going to agree with >>2 this time.

Is there anything I can do to test for this?

A voltmeter.  Or you could use some motherboard monitoring software.  Or just swap out the PSU with a verified working one.

>>1
Perhaps your mobo comes with software, like MSI's PC Alert, to show a graph of the voltages.

Are you sure you're back to your original settings in the BIOS? Have you tried loading the safe mode or the default settings in the BIOS?

You shouldn't try to overclock anything anyways; overclocking is very silly. Lots of trouble + compromising stbility for a lame 1 fps gain in your favorite game.

I've flashed the BIOS, updated it, brought it back to pure default.  I just picked up MBM 5 and thats logging my voltages and heat temps so when I do crash, I can read the last log entry and see if its abnormal.

Well, Just crashed and these were the latest readouts: CPU temp 122F.  Core Volt: 1.63(has not changed) +3.3: 3.28  +5: 4.92.  +12: 12.28   -12: -12.77   -5: -5.85.

Nothing has fluctuated and all held the same.

Those values seem to be within reasonably operating limits, though  the 17% error in your -5 voltage seems a little high.

As far as what's wrong, who the hell knows?  At this point, your best bet is to pull the ol' guess & check with presumed good hardware.  If you work at Best Buy you ought to be able to lay your hands on some.

You'd think so wouldnt ya.  We have very little test equipment.  Anyway I bit the bullet and bought an AMD 64 3000+ with a matching mobo for $215.  I figured if it doesnt fix it, fuck it I just got a decent upgrade :)

>>8
Those are good, save for -5V but I don't think it's too bad either. I see no problem here.

>>10
Was having a problem like this a few weeks ago.  Turns out my mobo was sort of dying.  Though I'm not so sure.. got a new one in, getting a BSoD or two a day now.. :(