Are you sure you applied the thermal grease properly when re-seating the HSF? Are you sure the HSF is facing the proper direction? If the HSF is mounted backwards/upside down, then it will end up sitting on the socket and you will lose alot of contact with the CPU. That could be causing your problems. If the power lead doesn't reach the designated slot, then find another, or get a lead extension. Most computer hardware shops should have these. Also, if you apply to little/too much thermal grease to the CPU when installing the HSF, then you could be adversly affecting the thermal transfer to the HSF. Check out these instructions:
http://www.arcticsilver.com/arctic_s...structions.htm
Also, when you installed the HSF with the grease, did you make sure to clean the bottom thoroughly, along with the heat spreader on the CPU? I use nap[tha (zippo lighter fluid) to clean off thermal pads or paste, and then go over it with denatured alchohol to make sure the surface is nice and clean. This will make sure any thermal pad residue is cleaned off of the HSF and processor. If you're going to use paste, you need to remove the pad, and if you are just going to use a pad, then you don't need paste.