I tried reseating the new HSF, to no avail. Still 50+C. This morning (about half an hour ago, really
), removed the new HSF, and applied the stock HSF. Temps around 20C. After inspection, and a little assumption, i realized the new HSF creates so much pressure on the CPU/mobo that it squeezes all the thermal paste to the outside edges, leaving the middle bare and complete metal-on-metal contact. Could be bad lapping, but i'll just stick with my stock cooling, seeing as how it keeps things very nice and cool, compared to the new HSF.
Thank you for your help, though! Definitely appreciated. BTW, i'm using Arctic Alumina.