I just recently replaced the stock heatsink that came with the AMD FX-8150 with a Cooler Master Hyper 212 Evo and have been having a lot of issues with my computer ever since.
I first noticed the problem when I was playing Skyrim, the computer just shut off after an hour of gameplay. I tried again and it happened even faster. So I tried a prime95 test to see if it was overheating and yep, it sure was.
I ran a Large FFTs tourture test in Prime95 and it lasted around 45 minutes until the computer overheated and shut down. Two out of the eight workers halted due to hardware issues and only six workers padded the 128k test. Here are two pictures with the amount of TIM I applied:

And here is the Prime95 error log:
[Wed Nov 07 12:19:03 2012]
FATAL ERROR: Final result was 00000000, expected: EEEC1181.
Hardware failure detected, consult stress.txt file.
Self-test 480K passed!
Self-test 480K passed!
Self-test 480K passed!
Self-test 480K passed!
Self-test 480K passed!
Self-test 480K passed!
Self-test 480K passed!
[Wed Nov 07 12:25:38 2012]
FATAL ERROR: Rounding was 0.5, expected less than 0.4
Hardware failure detected, consult stress.txt file.
[Wed Nov 07 12:37:36 2012]
Self-test 128K passed!
Self-test 128K passed!
Self-test 128K passed!
Self-test 128K passed!
Self-test 128K passed!
Self-test 128K passed!