My games still crash, it's not the video card

I bought another 260 gtx, from a different site. My PC just turns off, what does this sound like the problem could be?

 

sounds like a weak power supply or heat.What are the rest of the specs?

 

This is my PSU,

http://www.overclockersclub.com/vimages/ultra_x3_800watt_modular/9.jpg


Processor : E8400
Ram : Corsair 8 gb DDR 2
750i mobo
Case Cooler Master HAF (HUGE FANS and SIZE)

My temps, CPU at 29c and GPU at 38c

When I go into a game, it doesn't get that much hotter. So do you think when I go into a game it over loads my PSU?

 

what brand of video card did you get? Sparkle, evga, xfx? Some cards will crash with drivers from nvidia instead of manufacturer. Worth a shot at least. Use something like driver cleaner to get rid of all traces of the old driver.

P.S. if you have another powersupply to test or could borrow a friends for a day it wouldn't hurt just to rule out a power issue. I've seen the best power supplies go crazy.

 

It's an EVGA 260 gtx core 216 superclocked edition.