Comp restarts shortly after boot

[AlexK]

Yesterday, while playing a game, my comp restarted abruptly. It wouldn't POST, and was making a constant beeping noise. I opened the case, and found the MB chipset fan had stopped working. (The molex connector for fan had come loose from earlier, I think.) I got it going again, and let the comp cool down a few mins. Restarted, everything looked good. Windows loaded up, but about 5 mins or so... display blacked out, and comp started beeping again. And this happens everytime I turn comp on now. 2-5 minutes after booting, display will black out, HD will stop grinding, the beeping, fans/lights will still be going.

I've tried reseating vid card, and reapplied thermal paste to CPU after cleaning heat sink. Everything else seems to be connected and/or firmly in place. I wanted to get some help before trying other things. (like what would be causing display to black out/beeping)

Specs:
Windows XP Professional
AMD XP 1900+
1gig PC2100 ram
GeForce 3 Ti200

 

[Smokin-A.I.]

Sounds like one of two things may be deffective , vid card or psu. is the first places i would look ???