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.
A large FFT test caused my computer to exceed the TJ Max (90c) within 10 minutes. So I double checked my installation and noticed I messed up the x-bracket. So I removed and applied some new thermal compound and fixed the bracket. But now it overheats in under 3 minutes! I don't know if I applied too much compound or I sill messed up my installation. Here is a picture of the CPU with the compound I applied: