My pc also shuts itself down. Sometimes after hours of gameplay, sometime within 5 minutes of surfing the internet.
I can imagine that when it shuts down in the middle of a game it has something to do with intensive use of my video card. but when i check pcwizzard it shows me that none of my components are over 55 degrees celcius.
also when i open my pc all the vans are spinning and nothing feels overheated. my videocard feels warm though.
when my pc shuts down it tries to reboot but imediatly shut down again.
I cleaned my pc with an airduster ceveral times so i don't thing dust is a issue.
this problem is driving me crazy! please help me out