Lapping your CPU Guide

[Yellowhello]

Lapping your CPU

By Nate Phillips


Hello, and today I will be showing you how to get lower temps, better overclocks and a shiny finish on your CPU. Before we begin, I would like to get a few things out of the way: lapping your CPU will void your warranty and potentially damage the CPU and render the CPU useless. I am not responsible for any damage you will or have done to you CPU or yourself. Also, your CPU needs to have an IHS (Integrated Heat Spreader). Open die CPU's will not work. Wearing though the integrated heat spreader is almost a non-issue, but be aware it.

With that being said, lets begin lapping!

Materials you will need:

1. Sandpaper; I used one piece each of wet/dry sandpaper at 400, 600 and 1500 grits.
2. A pane of glass; I used one pane of 1' x 3'.
3. Masking tape
4. A CPU
5. Lots of time

All of these materials (except the time) is available at you local hardware store. The materials cost me about $25.

The brown sandpaper you see is a sheet of 800 grit, but it was never used because it had some weird resin coating, and did not want to risk it of my CPU.

I use such a large piece of glass because that way I am able to tape down multiple pieces of sandpaper and move from one directly to the next.

The CPU I used was the Intel E4300

Intel CPU's have a far greater problem as far as the surface of the integrated heat spreader. As you can see from the picture below, the thermal paste wasn't even touching the base of the heatsink, which is definitely bad. I have heard that AMD CPU's aren't as bad as the Intel ones, so I wouldn't worry about lapping an AMD CPU.

As you can see, the IHS was so concave on my E4300 that the center of the CPU wasn't even touching the CPU cooler!

On to prepping the CPU. I took two pieces of masking tape and covered the back of the CPU so that no nasty stuff like bits of metal dust and the like don't get in the CPU.

Now, actually lapping the CPU. Start with the roughest grit of sandpaper (the lowest number). Start sanding down the CPU is a straight line, from the top of the sheet to the bottom. Every 10 seconds or so rotate the CPU 90 degrees on your hand to keep the sanding even. The edges of the CPU should start to show the effects of the lapping and eventually some copper should start to wear though the grey coating (all Intel CPU's have copper under the coating of duller metal).

Keep lapping with the 400 grit until you can't see the dull metal coating. The CPU should have some reflective properties.

You can see the camera reflected already with just the 400 grit

Next move to the 600 grit. Some impatient people may stop at the 600 grit and that's fine because the CPU is definitely flatter than stock, but if you want a more reflective finish, I'd do the 1500 grit also. Do the 600 grit for maybe a minute, turning the CPU 90 degrees every 10 seconds.

600 grit

After that, move to the 1500 grit. The 1500 grit is just for a more reflective finish, as you are no longer trying to make the integrated heat spreader flat (you accomplished that with the 400 and 600 grits). Lap with the 1500 grit for 30 seconds, rotating the CPU every 5 or so seconds.

You can see the retention bracket of the CPU reflected after 1500 grit

I finished with 1500 grit, but some people may want to go up to 2000+ grits and some even buy rubbing compounds for a true mirror finish. DO NOT use polish, though. Polish fills in the dips that thermal compound are supposed to fill in. You will hurt performance more than if you don't use polish, so don't use it! The difference between polish and rubbing compounds is simple. Rubbing compounds act like a very fine sandpaper for a super flat and shiny heatspreader. Polish makes it shiny, but hurts performance for the reasons I just mentioned.

I would also like to add that shiny does not always mean flat. A heatspreader could be super shiny, but could have big valleys and dips in it. I test for flatness with a piece of lined paper. If the lines are reflected back with no distortion, the IHS is flat.

Testing for flatness

[Yellowhello]

Check it out, peeps!!

[Tyreal]

Very nice guide. I thoroughly enjoyed it although I wish you would have shown the cpu against some grid paper. I've been thinking about doing it myself but I can't justify the risk/benefit ratio.

[Dread]

Nice guide.

For perfectionists, you can buy 'float' glass.
Float glass is poured over a bed of mercury
to produce an almost perfectly flat piece of
glass, better than regular glass that has
imperfections in it.

You can also use rubbing and polishing
compounds after the 1800/2000 grit wet/dry
papers for an even better surface, just be
sure to clean the residue off thoroughly with
high grade alcohol before installation.

[Yellowhello]

Originally Posted by Tyreal

Very nice guide. I thoroughly enjoyed it although I wish you would have shown the cpu against some grid paper. I've been thinking about doing it myself but I can't justify the risk/benefit ratio.

EDIT: Dread, added a little thing about rubbing compounds at the bottom. Oh yeah, Ty, the only reason i would even attempt this is because the E4300 is cheap. I would never do this on a Q6600.

[Tyreal]

Nice. Looks flat enough. Poor man's way to measure flatness.

[robodude666]

Very nice helpful guide Yellow! If you don't mind me asking, what is the glass for? I sort of didn't catch that.

[Yellowhello]

Originally Posted by robodude666

Very nice helpful guide Yellow! If you don't mind me asking, what is the glass for? I sort of didn't catch that.

It's for a perfectly flat surface. A regular kitchen counter is not flat enough.

[sean126]

Good guide yellowhello....you did real good.

[Yellowhello]

Originally Posted by sean126

Good guide yellowhello....you did real good.

Haha, I used some of your suggestions when I lapped the CPU. Thanks, Scott!