It actually seems to do it more when it's idle or not under a heavy load. I thought at first it was the CPU overheating but I just cleaned it (the old paste was looking a bit thin and there was some dust around the edge of the plate) and re-applied thermal paste. After that I'm still getting restarts. I'm kind of stumped at this point as to what it might be. It could be the PSU but I'm really hoping it isn't because I can't afford to replace it. I'm not sure how exactly to go about solving the problem at this point (since I can't just swap in a new PSU and test that).
My system is a custom system running windows 7:
CPU: intel i7-860
GPU: nvidia GTX 470
PSU: corsair HX750w
Mobo: Asus P7P55D-ELX
HDD: 2x Western Digital Black Caviar 1tb + 1x Seagate Barricuda 1.5tb
Edited by stuckinreboothell, 17 January 2014 - 08:00 PM.