E6600 poor IHS contact - best sand paper for lapping?

My E6600 is idling at 43C (according to my P5B's BIOS) at stock--and I have a Scythe Infinity. Shouldn't it be more like 30C?

Anyways, when I take the HSF off the bottom is like 1/3 covered in paste, so the contact is pretty crappy. It's probably the IHS being concave and like many others I'll be lapping it with sand paper, but what's the best grade for flatness? Should I use water? I'll be going to Home Depot tonight to pick some up.

This might help you pick out what you need.

http://www.easypckits.com/products/premiumlk/

3M wet and dry

600 grit
800 grit
1200 grit
you can go finer but usually 1200 does it.
a lite touch up with a good polish after you have a uniform finish from the 1200, very lite touch up, you want to perserver the flatness you got from the glass and sandpaper.



autoparts stores usually have it only need a sheet of each use it wet.

do google of "heatsink lapping" its not the sandpaper that makes it flat its the piece of float (window pane) glass you put the sandpaper on. A modern pane of glass is amazingly flat.