Lapping

[joejccva]

What does lapping the heatsink and/or cpu mean? Is this something that has to be done prior to installing them on the mobo?

 

[kleinwl]

lapping is the process of grinding two parts together so that they have zero (or close to zero) tolerance (gap) between them. It is typicaly done in automotive for fuel injector parts (since tolerances are extremely small and are not manufacturable with normal processes).

A fine grit is put on one part and then it is moved against the opposite part until the tolerance is eliminated.

In a heat exchanger part (like a cpu/cooler) where a reasonable amount of thermal grease is used the efficency should not improve measurably.

 

[Greenman]

Unless your heat sink is really screwed up, lapping won't do anything.

 

[smithdj]

Originally posted by: Greenman
Unless your heat sink is really screwed up, lapping won't do anything.

Bingo, any slight gap will be filled with thermal grease and you are really wasting time and effort lapping it. When I see posts (on other tech sites) that people say "I just lapped my heatsink and I am now 5C cooler"' BS!

 

[eat2na]

Well. I purchased an XP-90 because of the smooth surface. When I tested it on top of my CPU I noticed that if I gently push on a top corner it would lift a little, like it was not sitting flat. I did some research and there are discussion about how the welding process of installing the pipes is warping the bottom of the heatsinks on XP90 and XP120's. I took a metal ruler and checked diagonally from corner to corner and oh my god the bottom is concave! When I point it toward a light bulb the ruler is touching both corner but as you move toward the center you can see the light. This can be confirmed by the way the sanding has barely put a dent on the center but all around it is all gone. I took an old scanner and used the top glass part and some 800 grade sand paper and have barely put a dent on the concave problem. Here is a pic.Concave XP-90

 

[Greenman]

Take it to a machine shop and have them fix it. Take them about 30 seconds and it will be perfect.

 

[cbehnken]

Glass is actually not that flat.

 

[eat2na]

Here are some pics of the final product and one when it still had a little concave spot in the center.Almot done!
Done. Mirror finish.

 

[us3rnotfound]

Originally posted by: eat2na
Here are some pics of the final product and one when it still had a little concave spot in the center.Almot done!
Done. Mirror finish.

:Q

 

[lobadobadingdong]

Originally posted by: us3rnotfound

Originally posted by: eat2na
Here are some pics of the final product and one when it still had a little concave spot in the center.Almot done!
Done. Mirror finish.

:Q

no kidding, you do know that coke with lime tastes exactly like coke without lime right?

 

[eat2na]

Not my drink. Prefer Pepsi. LOL

 

[mindwreck]

Originally posted by: us3rnotfound

Originally posted by: eat2na
Here are some pics of the final product and one when it still had a little concave spot in the center.Almot done!
Done. Mirror finish.

:Q

:Q:Q
maybe i should lap mine. squeeze a little more out of this before i switch over to watercooling

o yeah sprite>all