Computer randomly restarts itself

[sridge]

For the past several weeks an associates computer will randomly restart itself. Our first move was to switch wall outlets, which we did & it didn't work. Our 2nd move was to replace the power supply, which didn't work either. We have completely reformatted the computer (w98 2ed) and still, the computer still shuts off. Yes, we've even replaced the power cord. We've inspected the motherboard and it appears to be grounded correctly. Now we are stumped and looking for some suggestions!

[Confused]

What mobo is used. There was a problem with the first shipment of Epox 8KHA+ that there is a BIOS update for.
Chas

[Hpro]

Check RAM

[Hot Rod]

Is the power switch shorting out or a bare wire close to the metal casing which when it touches the case it would ground out.

[koryo]

Is the computer connected to a UPS power source? If not, try that. I had 2 computers that did the same thing & found out it was electrical power surges coming into my house from the pole. A surge suppressor alone didn't help, I had to go with one with a battery backup. Once I had it connected to the UPS, I had no more problems. To this day, periodically mine will kick over to the battery backup for no apparent reason. Sometimes it does this for just a second, sometimes long enough for the battery backup to start beeping. My power surge isn't enough to even make the lights dim in my house but it was enough to reboot the computer. Very frustrating, if the other suggestions posted don't help, try the UPS.

[sridge]

Koryo:
The computer was connected to a UPS and we thought that was the problem, so we disconnected it! We are still stumped. Beginning to suspect a bad motherboard....but are hoping that isn't the problem. The motherboard in a ASUS with an Athalon 800mhz processor. Heat isn't a problem because the fans are working properly. Hpro suggessted checking the RAM, so we will probably try that next. We've removed the modem, network card, etc. and the computer is still restarting itself randomly!