Computer Shuts off when Baking or Rendering

When baking for more than a minute or so my computer simply shuts off. I have an EVGA GTX 460 video card and a an AMD eight core processor and 16 GB ram, along with a 750 watt power supply. The same shutoff thing happens sometimes when I play video games. If I turn my computer back on right away, it shuts off again and I have to wait about a minute.
I suspect my video card has problems, because sometimes when doing GPU intensive things my display goes off and then on, and displays a message that my graphics driver had stopped working and then recovered.
I haven’t made any recent hardware changes. The problem just developed with no explanation.
It isn’t my CPU overheating because I checked the temperature and it never gets above 80 degrees C when running intensive stuff.
Might it be the power supply?
I know this isn’t a blender problem, but I would really appreciate any advice.

Hi Quacky

That happened to my PC. We finally figured out that it was the Graphics Card slot that was busted on the motherboard.

Is there any way to tell if it’s busted by looking at it?

Yes

I tested 2 graphics cards and both didn’t work.

I would try the power supply first, since it is the cheaper of the components. I had one go out here not too long ago, and a whole bunch of stuff was going weird, but it started with the graphics card first. I thought it was the GPU, but then it went to the keyboard and eventually I could see power fluctuations and knew it had to be the power supply. I had an extra one lying around, so I swapped out the bad one and placed the new one, and no more problems. Beats buying a new GPU or Mobo.

http://www.infoocean.info/avatar3.jpgWe finally figured out that it was the Graphics Card slot that was busted on the motherboard.