New build crash to desktop, can i assume its software?

Just built a gaming computer first build, my friend who is experienced and did the same build did most of the research on it for me. Everything has been simple and have had no issues to my untrained eyes, however... about 90 percent of the time when i go to play games ( Skyrim, Saints Row 3, Modern Warefare 3, anything else from steam) I experience what seems to be random crashes to desktop with no error. It mimics what would happen if I click the windows button or alt-tab.

I have been able to "fix" this issue by messing with my gpu tweaker, Nvidia control panel, and reseting defaults on my bios) however the CTD comes back up eithor after relaunching a game or upon restart of system. I am at a total loss, I want to troubleshoot but i do not even know were to start, my freind suggested that my PSU is faulty (I do not know how to determine if it is or isnt, I checked the bios voltage measurements and they match what is advertised for 3 V 12 V ect.)

I am completely pissed that my computer cannot do the one thing i poured money an time into for it to do, and i feel like this was a bad idea to even build a computer being that i have an issue that seems to have no solution.

my System is as follows,

ASUS Maximus IV Gene-Z/GEN3 LGA 1155 Intel Z68 HDMI SATA 6Gb/s USB 3.0 Micro ATX Intel Motherboard

SeaSonic X750 Gold 750W ATX12V V2.3/EPS 12V V2.91 SLI Ready 80 PLUS GOLD Certified Full Modular Active PFC Power Supply

CORSAIR H100 (CWCH100) Extreme Performance Liquid CPU Cooler

CORSAIR Vengeance 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model CMZ8GX3M2A1600C9B

ASUS GTX680-DC2O-2GD5 GeForce GTX 680 2GB 256-bit GDDR5 PCI Express 3.0 x16 HDCP Ready SLI Support Video Card

Intel Core i5-2500K Sandy Bridge 3.3GHz (3.7GHz Turbo Boost) LGA 1155 95W Quad-Core Desktop Processor Intel HD Graphics 3000 BX80623I52500K


OCZ Vertex 4 VTX4-25SAT3-256G 2.5" 256GB SATA III MLC Internal Solid State Drive


GPU temps, stay low when i do get my games to play around 36 degrees to 40 degrees. and when i am able to play i can go hours on end.

THANKYOU

Also I have clean installed twice

Just ran a stress test on my computer, Furmark, score was 4211 if that means anything. Gpu was able to run at 99 percent entire 15 minutes and nothing got more hot than 75 degrees. I don't know much but i feel like if this CTD issue was hardware related my computer wouldn't be able to survive this test, and my computer didnt as much as wince during the test