5870 problems after installing aftermarket cooler

[master noran]

Hey guys, I decided I wanted to install a aftermarket cooler on my 5870. After installing it the pc will give the post sound but nothing will show up on my monitors. I tried re-seating the heatsink multiple times and no dice. I also tried a different card and it works fine. I also noticed that on the post display the post code keeps changing to random post codes. The fans work and everything even though the fans power comes from the motherboard and not from the actual card.