PNY GTS 250 XLR8 Video card problems?

I recently bought two PNY GTS 250 XLR8 video cards and they run all games I play greatly, but I'm having a huge issue. When I'm in a game, I can play for like anywhere from 6-20 minutes, then my entire PC/system crashes, and I'm forced to restart by the power button.



The cards are NOT OVERHEATING.



Rig:



Video Card(s): PNY GTS 250 XLR8 x2 SLI mode



Processor: Intel(R) Core(TM)2 Quad CPU Q9550 @ 2.83GHz



Motherboard: ASUS P5N-D - nForce 750i SLI



Power Supply: OCZ Technology 850w PSU



Memory: Nvidia SLI-ready 8192MB (8GB)



OS: Windows 7 Professional 64-bit (6. 1, Build 7600)

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I've read online that uninstalling your drivers, then using a driver cleaner and then installing the 185.85 nvidia drivers would fix it but it didn't. I've tried the newest drivers for the cards, still didn't work. I've installed the original drivers off of the disc that came with the cards, also didn't work.



What else can I try?|||I just ordered a PNY GTS 250 myself, and the recommended minimum power for each is 450w.. so the minimum wattage for a power supply you need to be running just to be able to use 2x GTS 250 is 900w. You also have to take into account your computers power needs as well, so you probably are going to need a higher wattage power supply.



Just my theory.|||I would troubleshoot which hardware isn't working.



Test the video ram: http://majorgeeks.com/Video_Memory_Stres…

Test the ram: http://majorgeeks.com/Memtest86_d4226.ht…

Even a torture test: http://majorgeeks.com/Prime95_d4363.html



Good luck.