Lapping the base of your heat sink.

downhill · Post by **downhill** » Sat Mar 02, 2002 3:25 pm

Some here know I've been playing around, trying to lower cpu temps by various experiments.

I've installed a new HSF from Coolermaster. The HHC-001 You can see what I've been doing with it right here....

I've read a couple of post about lapping it but I can't remember who it was...so my apoligies.

I pulled the HSF this morning and got to work. I use 220 girt followed by 320 grit, and then 400 grit. (All was wet sanded) And followed that up with a quality metal polish and isopropyl alcohol.

First I'd like to point out that imho, the 220 grit was probably not needed and in hindsight, I should also have use one more finer grit.

I did not get the 3 to 5 degree drop in temps others have reported, but I did get a degree and a half drop.

Right now I keep my house pretty cool. I'm sure all this elbow grease will probably pay off this summer.

YARDofSTUF · Post by **YARDofSTUF** » Sat Mar 02, 2002 3:38 pm

i would have done 320 400 500 and them finished up, but sounds good!

RoundEye · Post by **RoundEye** » Sat Mar 02, 2002 3:58 pm

If your heatsink was fairly flat before, you may not see as much of a decrease as others.

When I worked for a company that did fuel injection work. We rebuilt the pumps and due to the high pressure, the internal pieces had to be perfectly flat.

anyway.....

I may go back there and see if they will let me use their lapping machine, this thing would lap metal to some kind of unbelievable spec.

m4a2t0t · Post by **m4a2t0t** » Sat Mar 02, 2002 4:01 pm

relap your heastink immediately,never use metal polish to polish your HS,it fill in the tiny valleys where the thermal compound is susposed to go thus decreasing thermal transfer.
i lap like this
400grit
600grit
1000grit
2000grit
all wetsanded u will get a very smooth finish and hardly any thermal compound is needed.

HawaiianGhost · Post by **HawaiianGhost** » Sat Mar 02, 2002 8:23 pm

Hey downhill, it was I that told you about lapping. Yes, do have to ensure that you have a flat surface on your heatsink as the end result or you will not acheive good heat transfer. I wish I could show you how my heat sink turned out (looks like a copper mirror) but I have to get a new cam. And you are probably right about which grit to start out with. I started with 220 grit due to the fact that I could see actual grooves from the factory like they had used a sandbelt with 150 grit paper.
Try using a pane of glass or a really flat and sturdy surface as your base with the sand paper on top of it. Avoid sanding with heatsink in one hand and sandpaper in the other this will cause uneven surface.
By the way I improved my cooling by 3*C by putting in a little more work into it. I had originally stopped lapping with 400 grit paper, then I got a hold of some thing called a "mesh kit" a couple of days ago. This kit has sanding grits with the following grades, all on emory cloth:

1500grit
2500grit
3200grit
4500grit
6000grit
8000grit
12000grit
*Kit comes with a detergent to clean off any metallic particles & all the grades are washable and reusable up to 15 times.

This Kit does great if you can get a hold of it from somewhere. I got it from a friend of mine. The one I have is a industrial sample, but I'm pretty sure that it is possible to get a commercial version from somewhere (try asking around places like an autoshop or hobby shop). It's actually designed for removing scratches from transparent acrylic finishes. The company that makes the one that I have is called: Sabine Production Center from Many, La.
Results from final Lapping (according to SisSoft Sandra):

-@ start up and for about 10min = 26*C
-idle = 30*C
-two music apps running two sound cards SB Audigy & SB 128PCI
=40*C
-After playing video games for about 2hrs straight = 43*C

And the Metal polish is perfectly fine to use as long as you buff it out and wipe off any excess polish. But ensure that you do use the right polish specified for that type of metal that you are using.

syncmaster · Post by **syncmaster** » Sat Mar 02, 2002 8:28 pm

Come on people even if you make your heatsings shine ,the gain is so litle that its not worth it ... why to spent time and money for some 0.0000000 Celsius or F ...

downhill · Post by **downhill** » Sat Mar 02, 2002 8:45 pm

Originally posted by syncmaster
Come on people even if you make your heatsings shine ,the gain is so litle that its not worth it ... why to spent time and money for some 0.0000000 Celsius or F ...

Ahhhh.......but Sync...your wrong my friend....with a little elbow grease, I've managed to drop mine around a degree and a half......

maybe not enough for some, but why not? As far as I was concerned, I thougt it was fun!

I'll have to find me some smaller grit......

I've made an 8 inch mirror for a telescope once. For the final rubbing, I used jewelers rouge..

Thats probably extreme...

HawaiianGhost

Thanks for the tips. By the way, I did use wet paper and a sheet of glass to keep it flat.