Polishing metal heatsink - require tips

[stormbind]

I have a Thermaltake G4-VGA copper heatsink cooler for graphics cards. Copper has high themal conductivity and this particular unit is quite substancial: way better than the wafer thin aluminium solution currently employed.

But then, when removing the unit from it's packaging I discovered a massive flaw in it's design! The underside of the heatsink is quite rough. Even with thermal compound, this irregularity will create insulating pockets of air (or compound) and seriously hamper cooling.

Reviews of the product show that it really underperforms, being only marginally better than stock coolers, and I'm pretty sure I know why. So I need to polish the belly of this heatsink and make is smooth...

However, I don't have the machinery to do that. How can I smooth the copper by hand?

 

[DaEezT]

I am no metal working expert but iirc copper is pretty soft as far as metals go, so you should be able to polish it using sandpaper.

 

[stormbind]

Are there any tips to go with that? I don't want to make it worse than it already is. At the moment, I would describe it as being like a very fine wood grain.

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For the record: There are also three cavities in the undersider, from partially-filled screw-holes connecting the fan. Bah!

And, the memory heatsinks are not copper. They are painted aluminium, too thin to be an upgrade for stock coolers, and only suitable for BGA memory layouts.

So if anyone is looking at this kit, it's only worth considering "as is" if you happen to need a replacement cooler for worn-out/missing original cooling.

 

[DaEezT]

I've never done it myself so I can't vouch for anything but I came across stuff like that on various overclocking sites. Only usful article I found is this but it's without pictures
If you want more info you can try looking through some of the big o/c sites/forums.

Oh, and I came across something interesting. It seems like polishing the copper blocks is such a common thing that there are Lapping Kits for it for sale

 

[stormbind]

That's great. I don't think anywhere near me sells such a kit, but maybe I will get lucky and find some 10 micron sandpaper at a hardware store.

Such a smooth finish should make a world of difference. Maybe make this cooler really worth having - no thanks to Thermaltake, who could easilly have done this back at the factory for £0.00001

Thanks!