Reason I ask is I had a KV8pro that I tried to use a stock cooler on it and the tension bracket was so tight it actually warp the motherboard and kept the memory from seating properly.
You can test this yourself by laying the computer on its side,pop the door off and just release the tension clip from the cooler.
With everything still connected and the cooler laying on the cpu hit the power button and see if it will boot.
If it does boot/post .DONT PICK IT UP AND PUT IT ON ITS SIDE>>>THE COOLER WILL FALL OFF!!!!!!!!!!!!!!!!!!!!!!!!
If thats the problem I would order a new cooler with a metal backplate so it doesnt warp the board when tightened down.
Good luck and post back