I have a custom built computer made for gaming that i built with my dad during christmas time. Everything has been runnin perfectly up until today. I got up and turned my computer on went downstairs came back up 1 minute later and it was off. I tried turning it off again and nothing happend. Then i tried again all the lights turned on for a second then it turned off. I flipped the power supply switch off then on then turned it on again. I was playing Call of Duty World at War for about an hour and everything seemed to be going good. I then went on Call of duty United Offensive when about 15 minutes into playing the computer just shut off for no reason. I booted it up again and again after about 15-20 minutes it happend again.
Please help me with this problem.
Intel Core 2 Duo 3.00ghz
4 gb ddr2 800mghz
Nvidia geforce 8800gt XXX
Apevia Xplorer case
650 W PSU
Cooler Master Hyper Cooler cpu cooler with 4 copper heat pipes
First I would unplug everything except your Power Supply (if it spins it should work). I had a similar issue and my Power Supply was bad it just booted once, then after some time would not boot, then I booted again after some time went by and it randomly shut off. My Power Supply was DoA so i RMA'd to get a new one and after that it has been perfectly fine.
Another thing I can suggest is check your MB temp and your Graphics temp and see if it gets to a certain temp and overheats etc.
Last thing I would do is run a Memtest for your RAM see if everything is ok. I had random blue screens on my vista machine after a certain amount of time which randomlyl caused it to shut down. My RAM (Crucial RAM) was ok, but I still crashed I then decided to try a different brand of RAM G.Skill booted up just fine, and never got any more blue screens/random crashes since then.