Why some sinks need lapping period!!!

[accurateimage]

WHy you should lap your heatsinks!!! You think your sink is flat??? Some are and some are not!!! These examples show how NON flat some sinks are!!! These two sinks are the chip sinks from a zalman heat pipe heatsink for the 9700 pro. The model # is HP-80A. This thing looked flat to the eye, looked flat to other people but when I started sanding it down on a 1/2" steet of glass I realized how NON flat this baby was!!! I literally had to start with 150 grit just to get i level and then polished it out by going up grit by grit to 1500. These pics just show how concave they are. The yellow area is the factory anodizing which is not even being touched yet by the paper! Now that is bowed!!!

[vee_ess]

Crazy. I'd hate to have one of those cause an OC'd processor or video card to burn up. $.40 worth of sand paper can save so much.

[CiKoTiC]

I've read the Zalman was supposed to be that way.

[accurateimage]

no way man, why would it be? made a hell of a difference once lapped, that is like saying my tires are supposed to be unbalanced!!! Upon lapping my sink was allot hotter which means it was making good contact, the 80mm fan that cools it blows allot more warm air also!

[CiKoTiC]

How big is the ATI GPU and how big is the actual die the HS sits on?

The curvature was to accomodate the metal shim around the GPU.

I rest my case. 8)

[accurateimage]

dood, look at the sanding parks *LOL* the outside is higher than the inside!!!!! If it was to accomodate the shim the middle part would be lower!!!!! *LOL* the ati gpu is quite large, over 1/2" by 1/2"

[CiKoTiC]

:rofl:

Hehe.. I was thinking it was the other way around!! Sorry bout that. :shake:

Note to self....lay off the crack for awhile. :nod:

[accurateimage]

haha it's coo :) the latest versions actuall have a machined edge in it to fir the shim but the actual surface is still not even close to flat which kinda defeats the purpose!

[CiKoTiC]

Yea, mine is machined to accomodate the shim.

I took the shim off this ATI card and with the HS machined, I don't think lapping would do any good.