lapping the cooler?

hi, i just got a 9800 pro 128 mb ati and i also bought the VGA Silencer rev 3 and want to put it on my card. But i was told to lap the cooler which suposobley means to use 5000 grit wet dry paper and sand it down to a mirror finish. Its suppose to help with the heat alot. could anyone help clarify this for me. possibley give a link to some instructions on how to do this if it is even possible.

Thanks,
Tomek

5000? Sheesh, I've never used that fine of a grit to lap. I tape automotive grade wet dry sand paper to plate glass and then put the heatsink down flat on the sand paper and move it around in a figure 8 motion. If the heatsink has a lot of machine marks or is fairly rough, you might start out with 400 grit. If it's already pretty smooth, then go right to 800 grit. Just be careful with the coarser grades. I usually start at 400, then move to 800, then go to 1000 or 1200 depending on what I have on hand. The highest I've ever used is 1500 grit and that will get a heatsink super smooth, almost like a mirror if you are careful. I have never noticed any significant temp improvements by using a grit finer than 1500.

I generally begin with 800 and move to 1200 and finally a few passes on 2000.
Maximus has a groovy guide with differing grit suggestions (we all have our methods) here.





EDIT: While less so regarding GPU and NB blocks, the industry as a whole has responded to user's expectation of SOME sort of flat surface, and even the laziest of manufacturers will at least make it SEEM flat. Because of this.. often the coarser grits are less advantageous.

I went as far as 1500 grit paper.... still had a mirror shine to it after using the buffing compound.... 5000 wouldn't hurt but man, talk about overkill....

heh alright thanks alot for the quick reply, im gonna try that out (hope i dont mess up )