here is another tip when doing your heatsinks, make sure to de-burr the holes you drilled to make it flat, you can use a bigger size drill bit to do it, say 3/8, then you can lap your hatsink by laying a 600grit sandpaper on a flat surface, prefferably a glass table top, then rub the mounting surface of your heatsink on the sandpaper using regualr even pressured motion, this will ensure that the chip package will mate evenly withe the heatsink, thus more efficient heat transfer can be achieved...if you want you can clean you heatsinks using a lye solution, half a can in a pail of water would be enough..do this in a well ventilated area such as outdoors, as you immerse your heatsink, a pronounced bubbling will take place, half an hour should do it...you can use vinegar to remove any stubborn stains, but in my experience i never had to resort to this...depending on the strenght of the solution and the soaking time, you can have a silvery matt finish....take care!!!!
