Sorry if this is the wrong place, but this seems tp be the most general forum, seeing as I don't know what the source of the problem is...

The problem is my compiuter instantly powers down for some unknown reason, this seems to only be when its under load, and may happen after just 2 minutes, or after hours (eg playing a game, long compiles, etc), but Ive never had it happen when idel or say browesing the web.

After this the only way to restart it (it just acts dead otherwise...) is to completly cut power (eg disconect the power supply) for around 5 seconds, simply leaving it doesn't work (eg I left it from going to bed, to getting home from school and I still had to disconect the power supply to make it start).

At first I thaught it was a overheating problem, and that it was shutting down to avoid damage, however after moniterring the temperatures ive found that it isn't at a certain temperature.. (eg the CPU could be anywhere from 40C to like 60C when this happens...

I then tried changing the power supply but the same thing still happens.

System specs:
Windows XP SP2
AMD athlon XP 3200+
nVidia GeForce 6600
Old creative soundblaster - I'm only using this for its gameport, not for sound since the mb doesnt have one
Motherboard -*looks for lable/manule* well if someone can tell me how to tell since I built this computer 2+ years ago...

ST340810A (40.0GB) << Single partition, windows
Maxtor 6L200P0 (203.9GB) << 2x40GB partitions, the rest is currently unformatted


Usb devices:
Segate FreeAgentDesktop USB Device (250GB)
Trust 5.1 Surround USB Headset

Take a look at System Info for Windows. This will give you the info on your systems hardware.

As for the shut down problem try another video card and see if that helps. If not then test your memory let the memory test run over night. Replace it if you have any errors.

Is the power supply enough for what you are doing, i mean it could be that power supply may not be enough. You did not mention what power supply you had before and what you changed it to.