So my build is as follows:
MSI P55-GD65 Motherboard
Corsair XMS3 DDR3 4GB RAM
EVGA 9800GT 1GB
Intel Core i5-750 at stock 2.67Ghz
Logisys 575W PSU (http://www.newegg.com/Product/Product.aspx?Item=N82E168...)
Occasionally, the system shuts down for no apparent reason. My video card is around 66 degrees Celsius, and my CPU isn't overclocked. This is mostly after playing Battlefield Bad Company 2, but I can surf the web for a few minutes, and I see the Graphics Card temp dropping to around the high to mid 50s. Then, it just shuts off. When I try to boot into Windows(7-64bit), i make it as far as the login screen or just a minute or less in, and it shuts off again. After a few minutes of leaving it shut off, it boots up fine. Does anyone believe this is a Temperature problem with something in my system?
I think you should pull your cooler off, clean off the paste, and reinstall with new paste. If you really want to check this out though you can install coretemp and watch the temps while you game. This will tell you if there is a temperature problem.
Concur with above on monitoring your cpu/gpu temps under load. I normally run Furmark in a window to stress GPU. Have you run Prime 95 to stress CPU/memory.
Also Lower on the possibility list is a heat/voltage problem with the PSU.
So add monitoring your +12 V and see if it starts dropping prior to computer powering off. (Repeat this is less likely, but easy to rule out)
My CPU idles around high thirties and low 40s, but gaming puts it to about 50's, the highest ever being 66 (Celsius). I really feel like it's a psu issue. I was cheap, and it was only $30ish. I'll go with a new one. Thanks guys.
66 is a totally acceptable temp for the i5 750- I have one:-) This sounds like a PSU to me as well. Let me tell you my first rule of building a PC- NEVER SKIMP on the PSU! :-) Its a good way to blow out all the expensive parts you just bought. If it shuts off and stays that way for a few minutes, and then eventually you can turn it back on, your PSU may be overheating and failing and shutting off. I would pick up a DECENT PSU (corsair 400 or 450W should be enough) and see if that helps. If that doesn't do it, I would run a memtest and see if your memory is having trouble as well (though it will generally give you a BSOD, sometimes it can just shut off.)