computer rebooting for no apparent reason

[ny_driver]

ABIT AV8 K8T800pro
athlon64 3500+
2x1024 supertalent ddr400
HIS 9600pro family 256mb
antec 420w PSU
acer 22" LCD monitor model p224w
windows xp pro sp3 fully updated

My moms computer just reboots itself occasionally. Not during any one particular activity, just whenever. She doesn't do anything real graphically intense and doesn't really do much multi-tasking either. Because her old computer also did this rebooting thing, I have suspicions about the monitor. It could also be the PSU, although I replaced that (with a used one) when I built her new rig. I replaced everything except HD, CD-drive, and floppy-drive. I suppose it's possible that the old PSU was faulty, and the new used one is also faulty in the same manner.

I'd love to hear some other ideas. Thanks.

 

[Exeodus]

My first guess would be power supply. Do you have a tester?

 

[ny_driver]

you mean a multimeter? yes.

 

[ChiSox]

You reinstalled the OS?? It could be something like a pci card, dvd drive video card...I would pull each piece of hardware out individually and test til its not happening anymore...Ive also had freezing from keyboards

 

[AsRock]

Check the ram stick by stick see if ones dieing ( Some times the BIOS memory diagnostic picks errors up to other wise use memtest). Try another PSU in the system if possible.

Could also check the HDD for errors too.

 

[ny_driver]

I checked the HD using HDTune, the ram has been memtested. It's gotta be PSU I guess, but very strange how two different computers are doing the same thing with different PSU. Like I said the only things that stayed the same are HD, CD & Floppy drives, and the monitor.

 

[AsRock]

Maybe it's just windows playing ass lol ?. Or even some program she uses ?.. Any chance you have a spare HDD so you can reinstall windows on it and see if it still happens ?..


Maybe one of MS's drivers been installed for a piece of hardware and messing things up ?. As their drivers do suck too.

 

[ny_driver]

yup I got a spare 40gig HD. Hmmmmm what a pain. That's the thing to do though. Process of elimination. Thanks for the ideas.

 

[sonnytiger]

Might be the CPU overheating, they shut off the comp for safety. If there is alotof dust it will do that especialy if its a stock cooler

 

[ny_driver]

Might be the CPU overheating, they shut off the comp for safety. If there is alotof dust it will do that especialy if its a stock cooler

It's all clean and freshly installed with AS5, I don't think I've seen it above 40c. My mom doesn't do anything to stress the cpu anyways other than some puzzle games, and scrabble.
EDIT: I'm going to go test the PSU now.