I just recently finished a lil project, which many of you would call crazy. I over many builds have seen the benefit of lapped heatsink to a non-lapped heatsink. So I got to wonder about lapping the heatspeader on a processor. I read three guides and the results turned out ok. First I'll say that this was not on my new pentium D (i am not that crazy Yet), it was on a celeron D 2.4GHZ. Second this takes a long time(wanting to be careful, and going through all the grits: 220, 320, 400, 600, 800, 1000, 1500, 2000, 2400, 2800 really hard to find). After the lapping you'll find must of these heatspeaders are made of copper. After lapping the heatsink (with all the same grits), I found a dramatic drop in temps(most like do to the flatter surface on both Heatsink and Processor) the Idle temps dropped from 39C idle to 23C 8O . This was with an intel stock HSF that i lapped, I just wish I that the mobo I have for this rig could overclock. Yet again this was an older rig I didnt care if I messed up, I don't recommend this unless you have alot of time and your very careful. The processor took me 2 days to lap(I was going very slow to be careful not to damage the CPU), the Heatsink 5 hours.
what i mean by lapping is to make the surface as flat and smooth as possible with sandpaper(auto sandpaper wet/dry) and a flat surface(a sheet of glass). By doing this the processor and heatsink cames into more direct contact with each other and this promotes better thermal transference.
This is the whole reason we use thermal paste. its so much quicker and cheaper than spending 8-9 hours doing figure 8's on sandpaper. and after the curing period you see almost the same 5c' drop.
also there is no reason to start at 220 grit start at 400 or 600.
i am a machinist by trade so i do have actual money makin experience.
we only go to 600 grit for hi-power amp(1 watt at 60 ghz) to hsf as an example!
so if i lapped your processor figure about $50 ph. cause i can get down to 4000 grit lapping compound, even go to 5000 if ya wanted too. this is liquid almost.
well I started that low cause the processor was concaved and i could see that by how it scarred the heatsink(scars are gone after lapping). Overall i am very happy with my results and temps( i used artic silver 5, before I lapped and after I lapped). Btw where do you find the higher grits.