Heat sink help

Here's My issus i have a GA-M57 sli-s4 swapped out a BE 5000 for a X4 940 Here is the strange thing the stock HS or my freezer 64.

if i lock the heatsink 100% the cpu
wont post.? if i lock it 50% works fine idles at 28c if the case is flat then jumps to 40c when its stood up

I know its from not seating well between the sink and the cpu. looking for options or ideas thanks wdmso on what might be the cause did not have this issue with the BE 5000

Theses heatsinks dont have push pins , they clip then lock in place with a lever