I built this system a in April and recently upgraded it adding a new CPU, GPU, and CPU Cooler.
Everything was running OK, until the last upgrade of the CPU Cooler. Installed a CM Hyper 612PWM.
Runs fine under light loads. During heavy gaming it shuts off after about 15 min. No warnings or alarms before or after. I have a 2nd monitor with AIDA64 running on it and the temps never get above 70 for the CPU.
Try reapplying thermal paste to the CPU. If if its doing it under heavy loads, it could also be the GPU overheating. Try replacing the new GPU with the old one, (New CPU and old GPU) to see if it does the same problem. this will rule out one of the options.
Update: Turns out AIDA64 stinks at reporting accurate temps. I also must not have saved the BIOS settings with the alarm on. Switched to CoreTemp, made sure the BIOS was saved, and it is definitely the CPU overheating.
After reinstalling the CM cooler (same behavior), cooler master said the cooler is bad. I guess the bottom of the CM cooler is not flat, or something is wrong with the heat pipes. Back to newegg with you, POS......
I reinstalled the stock cooler and no issues. Except for the airplane noise under my desk.....
I'm getting a AC Freezer A30 instead. I may have to pop the heatsink off the closest RAM stick, but it will be worth it.
I just installed an AC XTREME 7970 on my HD6950. Other than the crappy directions and length of down time to do the install, it is awesome. It took 24 degrees C off my GPU temps, AND you can't hear it!!!! Had to stick my hand down there to see if the fans were running.
Their tech support was really helpful in figuring out the best placement for the glue on heatsinks. The directions only show 7970 placement. Downside is they are in Switzerland, so communication is not the fastest.....