As mentioned above, remove the current paste and reapply as part of attaching the HS. I would also recommend keeping components in their anti-static packaging until you are ready to actually build out your computer. It is find to put the motherboard back in its packaging with the CPU installed. Objects around the board that do not touch should not cause any issues... unless you have a tesla coil next to it. DO NOT run the motherboard without the HS installed. The CPU has a very small surface area for dissapating heat compared to the HS as the HS has the area of all of its cooling fins combined.