[Fixittt]

Chip from Lufken tech (SP) that I beleive has long sold out. He made a direct die cooing block, and tried pumping the hell out of it. From what I read, a few people lost there rigs due to it. And even more were against the idea. At least with copper, the block can absord and move the heat away from the core, allowing the increased surface area of the waterblock to preform better.

Also on one of the forums, I read an article, where a guy who works with lasers, ran a comarison test lapping different heatsinks to different finishes, with different amounts of goo. He was cooling some hot parts of the laser. He concluded that a wet (Using water or WD-40) as a lube, worked better for him then a highly lapped surface.

my 2 cents

edit:
Ok I have 2 more cents.

Seeing as the cores are not perfectly flat, you need to use some sort of goo. No matter what. Actually the pits in a core are quite big, so artic silver of some sort is recomended. So if you have a gritty substance (Artic silver) and tried putting a mirroed finish cover over it, wouldnt that (For argument sake) lift the mirrored surface off the core? So why not have 2 roughter surfaces so that the artic silver could effectivly fill both surfaces, bringing them closer. Also I think it should be said that before clamping anything down, the block should be rotated on the core to work the paste into the cores surface as well.

But then again I could be wrong.