Lapping a heatsink and CPU

PokerDegenerate

Daemon Poster
Messages
1,465
OK so I have been doing a lot of research on lapping. I have never done it before (obviously or I wouldn't be doing research right) I am seeing a HUGE difference in cooling results. I am wondering though is there really anyway I could screw up my processor doing this? As long as I just use a flat glass surface and the correct sandpaper all should be fine right?

Also this is obviously going to void my warranty I am assuming as well with my CPU so any suggestions on whether I should just hold of on CPU and just go for HSF for now and just take those results and be happy. I just feel that with the results I am seeing other people get from this I really wanna give it a shot. I have an extra stock AMD heatsink laying around that I am going to give it a shot on for a test just to see some results but I don't have an extra CPU to give it a shot on but I am just scared that as soon as I do it something is going to go wrong (not necessarily with the lapping) but with the CPU and I am going to be pissed for voiding the warranty on it.

Any suggestions from those that have done it?

Also any pointers from those who have done it?
 

worshipme

Golden Master
Messages
5,603
It's very satisfactory once it's done. Although it does require patience, you'll want to do the CPU once you've done the HSF.

Get a slab of glass, and I think I used 400, 600, 800 and 1000 grit, I tape the sand paper down so it doesn't move around.

Do not do figures of eight, it will be hard to apply even pressure. Do not put too much pressure on the CPU/HSF, just light, even pressure with your hand.

I usually do a complete 360 degree turn before I move onto the next grit. I don't mean that I turn it in circles, I only go up and down. I'm sorry, this is very difficult to explain. I'll try and find a video on Youtube showing the technique I use. I lap the CPU one way for a period of time, rotate it 90 degree and repeat until I have turned it 360 degrees. If I'm still not satisfied I will repeat, otherwise I'll move onto the higher grit.

EDIT: Here is the EXACT technique I use: http://www.youtube.com/watch?v=sVXuZTuoEuE&feature=channel_page

I used to lap up to 2000 grit but I realised that it didn't affect the temps at all and was a waste of time. Remember, it just needs to be flat, not shiny. Try to get the surface as flat as possible with the low grit before moving onto the higher grits.

You may find it easier to wet the sand paper slightly at the higher grits as it will help the CPU/HSF to glide better. If you feel uncomfortable wet lapping the CPU, that's fine.

And I personally found AMD's IHSs to be a little flatter than Intel's, so good luck.
 

PokerDegenerate

Daemon Poster
Messages
1,465
Thanks worship:

About the CPU that is exactly my thoughts too because when I see the results from the HSF I know I will be thinking to myself well how much more cooling will I get with the CPU done too.

I also found a kit for like $6 bucks that comes with 400, 600, and 800 grit sandpaper and then also comes with lapping compound which is basically the same thing as using the higher grit sandpapers from what I am understanding. I'm not worried about how shiney it gets really because all im gonna do is smear the Thermal paste on anyways so its just really getting it flat and free of the machining grooves. I did see that going in the up and down motion is the best way and from what I understand you just do it in 1 direction then rotate 90 degrees do it that way and just keep turning till you made it all the way around the area your lapping.

I was just planning on like you said using a tad bit of water on the sandpaper to lessen the friction a little bit. Did you mark it with a marker as well since Ive seen alot of folks did that as well to kind of judge if the whole thing has been touched which helps with the flattness I guess.

I guess I am just going to give it a shot with the stock HSF first and see how well of a drop I get and to get a better feel for it and then Im going to mount my new HSF when it arrives get some temps and then take it off and see how much of a drop I get.

I might make a video or take some pics and then make some graphs to post up here when I do it as well so that others can see the process if they arent familiar with it and check out some graphs with prelapping temps and postlapping temps.
 

Cabbs

Golden Master
Messages
7,912
I used dish soap for the wet-sanding, but it doesn't really matter. You should see some gains though, I lost a few lapping my TRUE and CPU.
 

worshipme

Golden Master
Messages
5,603
I was just planning on like you said using a tad bit of water on the sandpaper to lessen the friction a little bit. Did you mark it with a marker as well since Ive seen alot of folks did that as well to kind of judge if the whole thing has been touched which helps with the flattness I guess.
Yes, I did used to do that, I'd mark an X from corner to corner. This will show you whether the area is concave or convex and when it will have disappeared when it's flat.
 

PokerDegenerate

Daemon Poster
Messages
1,465
cool thanks for the help guys I decided not to go with the kit but to just go get some wet/dry sandpaper from the store so that way I have some for the future as well since the kit only comes with a small amount of supplies really only good for 1 use so I would rather just get enough to do some tests with as well.

@ cabbs I saw that some used dish soap as well for the wet sanding and was actually thinking it would be better that way with the CPU just incase. Im not hoping for miracles but anything cheap that will give me some gains im all for it.

From what I understand some people really dont get much of a gain since the HSF/CPU is already flat but just needed a little of the grooves removed. But hey every little bit counts since I don't want to hit a heat barrier OCing before I hit the frequency barrier...:D:D:D

Thanks again guys
 
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