Computer randomly shut's down in game

[Jasonz]

Despite other games running fine, I think it's a hardware issue. Here are some tests you can run:
Running Furmark for 15 minutes or so will rule out the possibility that your video card is failing or overheating.
Running prime95 and Furmark at the same time for 15 minutes will usually rule out the possibility that it is a power supply issue.
Running memtest for a few hours (or over night) will rule out the possibility that this is ram related (this must be run from bootable media).

You said that you set the max fps to 60, but that might not make any difference if the computer cannot produce more than 60 or if vsync is enabled. You could try setting it to 40 fps and ensure that the system is easily able to handle that (if not, lower resolution or turn off AA or anything that is slowing it down). If it is a hardware problem, reducing the strain on the system may stop it from crashing without having to replace anything.