Computer crashes during launch of higher end games - hardware problem?

I just built this PC last week. I was able to play Half life 2, SC2, The Witcher, & Oblivion on highest settings without issue.

I tried to play the Darkness 2 demo and when it got to the intro video the screen froze and then the computer restarted. I tried again and it went to a blue screen saying the computer is being shut down due to an error with a clock interval...or something like that.

I tried playing Portal 2 and it again crashed during the load screen. Then I tried Overlord and the game crashed, but it just went to the desktop saying something like "The program has encountered an error and must shut down."

I'm not sure what the problem is...

I tried running the oc scanner and stress test the gpu, but I couldn't reproduce the problem.

I made sure I had the latest drivers for the gpu & mobo chipset. It seems like a hardware problem either with the gpu or the mobo, but I'm not sure how to isolate the problem and rma the faulty hardware.

Any suggestions how I can figure out what's causing the problem?

OS - Windows 7 home

CPU - AMD FX-8120 Zambezi 3.1GHz Socket AM3+ 125W Eight-Core

MB - ASUS M5A88-V EVO

RAM - Kingston HyperX Blu 8GB (2gb x 4)

PSU - Thermaltake TR2 RX 750W Bronze

GPU - EVGA 01G-P3-1460-KR GeForce GTX 560

HD 1- Corsair Force Series 3 CSSD-F60GB3A-BK 2.5" 60GB SATA 3

HD 2 - Seagate Barracuda Green 1.5TB 5900 RPM 64MB Cache SATA 6.0Gb/s 3.5"

Sounds like it's your PSU more than the motherboard. I had that same issue where my computer would shut down when I used anything that wasn't running the system on idle (games, etc). I eventually determined that my PSU was at fault, swapped it with a Corsair TX 750 and been problem free ever since.

Yeah 550 is pretty typical, 750 is ideal.

If it's the RAM you can try removing each module and powering your system on one by one to see if there is indeed a faulty module. It's a huge pain, I know, but there really isn't any other way to test faulty RAM.

Alternately something could have been screwed up in the BIOS - try loading your defaults and see what happens.

I'd suggest contacting your motherboard manufacturer's tech support to find the problem and possibly RMA it.