What would cause this system to freeze randomly after building it?

[Th_Redman]

I recently started building and servicing computers, mainly desktops but the odd laptop and my roommate asked me to build this system for him(about a month ago now) and he recently told me that while watching Youtube videos and a movie that the computer just freezes, hence a reboot. First, here are the pertinent specs:
CPU-AMD FX-8120 8 core processor
Mobo: GIGABYTE GA-990FXA-UD3 AM3+
Video card: AMD Radeon HD 6850 1GB
RAM: Corsair DDR3 1333Mhz 8GB (2x4gb)
Power Supply: a new Coolermaster Extreme Power 500watt
Hard Drives(2): 1-500 GB W.D. Blue 16MB cache (primary with Win 7 and software programs), 1-1000 GB W.D. Blue 16MB cache(secondary-used for storage-movies, music etc).
Now after putting it all together, of course I updated all the drivers and ran a few tests (memtest, futuremark and others) and it ran perfect. Also told him to update windows 7 anytime windows updates needed updated (sorry for using the same word over and over lol) I read that the AMD FX processor line uses a "patch" in Win 7...could that be what causes the random freezing and it needs that patch? Or could it be something as the power supply not being that great (I know it's a Coolermaster 500 watt). I welcome all responses.

 

[toritedo2003]

You may need more ram on your video card, though OCing can cause this problem. Although 8gb of ram is plenty, try adding another 8gb to see if it frees it up. Check the temp on your video card and CPU. One GB of VRAM sometimes is just not enough. Is it GDDR5 or 3?