Alrighty, so I have been having crashing problems. I would play games for a little while then under certain load my whole computer would shut off. I figured it was my video card (MSI Twin Frozr II 5830). So I did a stress test on my card and CPU. It turned out to crash on my card. So I unplugged the card and ran off my motherboards graphics. Everything ran absolutely fine. I had no problems I even played Blacklight Retribution (Though it was horribly slow). So I really was positive it was my card. I then went out and bought a new card, a XFX 2GB 6950. Plugged it in today and the problem still exists only it happens sooner. I can't even get to the game menu. This makes me think its the PSU. Since this card requires a bit more power and adding a card would cause my PSU to hit a certain peak. I think once the video card gets going and puts more of a load on the PSU it decides to shut the computer off, but it's unlike a normal shut off. My keyboard, mouse, and display will shut off and my fans will keeps going. I cant turn it off by hitting the power on my case I have no idea why. So I have to hit the power switch on my PSU. I'll turn it off and let it sit for a few seconds before I go and turn the computer on again. It will boot up fine after this. The computer can be a bit finicky once it boots up, but it's because it's booting from a crash. A proper reboot fixes that. So I want to ask the wonderful community of people who know more about this stuff than I do on here whether you guys think it's the PSU or another component. I'm very much hoping its just the PSU. Thanks!
At first reading it does sound very much like the PSU is the culprit. However, although yougave good details of your GFX cards, you have not said what CPU, Mboard, and most importantly which PSU you have.
Please give us your full specs so we can help you more.