GTX 295 & Power Supply

Hi guys,

I've been having problems with games causing my system to reboot as soon as they load. I'm using a GTX 295 with a Thermaltake Toughpower 750W PSU. This happens most often when I try to run games at high resolutions. For example, I can play the witcher at a lower resolution, but when I put it to 1920 x 1080, the computer shuts off instantly and reboots itself. Some games -- Tropico, Risen -- Will do this as soon as I start. I have 6 gigs of 1600 mhz ram and the i7 920. From what I've read, this sort of problems seems to be a PSU problem. I'm thinking about upgrading to an 850W unit, but I wanted to hear everyone's advice first.

Oh, one more thing to note -- I do have a lot of peripherals -- external hard drive, blu-ray drive -- but even after unplugging them the problem occurred.

Thanks!

I should say, I've played a number of other games that have worked very well, including ones in 1920 X 1080. I should also mention that my PSU will rattle slightly from time to time; this is one of the main reasons I thought it might be the culprit. The temperature and the drivers are fine. I am a newbie, but what puzzles me is the sudden nature of the shutdowns -- the system never chugs, and runs perfectly fine except during these times when it reboots with no warning.

As I said, I am a bit of a newbie -- what am I looking for in those tests?

Well, I tried a friend's Corsair TX 850 and it's running like a charm. I suspect, because of the clicking noises, that my PSU was powerful enough, but just faulty. Thanks for the help guys.