Originally Posted by
Auberdeen
It's probably most definitely the power supply being overworked. 600w is a bit low for a monster gaming rig, especially since most 500-650W PSU are partitioned off into 1 400W/1 250W within the same unit.
Look into a 800-1000WPSU and make sure its a full time 700W+ for the first partition if it is in fact, partitioned.
You can see what yours is by opening up your rig and looking at the side of the PSU, it will look something like this:
[.IMG]http://i54.tinypic.com/2mfxljl.png[/IMG]
it's probably getting a bit overworked.
if not this, I would say possibly your cooling unit. Make sure you put enough thermal paste on your CPU. go into your BIOS and make sure THE CPU is running cool, not just the temperature of your comp.