Clueless as to why my computer is freezing during games.

Hello, I posted a couple days ago on my issue and just want to make sure there is nothing else I can do before I send my video card out to be exchanged.

Problem: While playing games my computer will completely lock up and force me to restart it manually. This has been happening at random times while gaming and everything is running very smoothly just before this happens as well. Once in a while my computer will be able to recover and i get a message telling me that my video card drivers have stopped working but recovered successfully. I've run memtest and windows memory diagnostic and everything turns up fine. I've stress tested my card and it's max temp was 62 degrees Celsius. I've also tried different video card drivers and made sure that the integrated video card is disabled and updated my bios.

My specs: CPU: Intel Core i5-2500K 3.3GHz Quad-Core Processor

Motherboard: ASRock Z68 Extreme3 Gen3 ATX LGA1155 Motherboard

Memory: Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory

Hard Drive: Samsung Spinpoint F3 1TB 3.5" 7200RPM Internal Hard Drive

Video Card: Asus Radeon HD 7850 2GB Video Card

Case: Cooler Master HAF 912 ATX Mid Tower Case

Power Supply: OCZ 600W ATX12V / EPS12V Power Supply

Operating System: Microsoft Windows 7 Ultimate SP1 (64-bit)

Thanks for the help, I really appreciate it!!