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Atomic guide to CPU lapping

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Atomic guide to CPU lapping
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By Justin Robinson
Jan 23, 2009 | 20 Comments
Tags: CPU | heatsink | lapping | tutorial | guide

We give you the low-down on how to get your CPU and heatsink flatter - and running cooler - by lapping it to within an inch of its silicon life!

In the mad enthusiast rush to squeeze more clocks and speed out of our gear, there are a few hurdles along the way that hold us back, one of the largest being heat. Heatsinks draw it away from the CPU, and radiate it, but it is in this step that they sometimes fall down.

Assuming ours is a perfect world, every heatsink would have a perfectly flat base, and every Integrated Heat Spreader (IHS) on a CPU would also be flat, needing only a smidgeon of thermal goop to provide the material needed for the very small gaps between them. Sadly, our assumption was a little misguided, and neither of those things exist.

The IHS on a CPU is nearly always extremely convex (raised in the middle, and falling off towards the outer edges), and is made of copper coated with nickel. We’ve chosen the Core i7 920 chip (mostly because we’re crazy, and have no respect for misbehaving tech) and a
Thermalright Ultra 120 Extreme 1366 cooler for this experiment, and we’ll show you not only how to get great results for little money, but what we managed to achieve.

Running our CPU at idle, we recorded the following temps at idle, and at load under OCCT after a period of twenty minutes:

Core i7 920 - Idle
Core i7 920 - Idle


Core i7 920 - Load
Core i7 920 - Load


Click on to see just what we do to it...

 
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20 Comments
Thoughts on this article? Add a comment below.
iamthemaxx
Jan 23, 2009 4:59 PM
 George St, Sydney called.
It want's to know if you have finished lapping as it's wearing away!
LordBug
Jan 23, 2009 5:22 PM
 WTF?
BMP images?
Slaaaaaack!
:P
nesquick
Jan 23, 2009 5:41 PM
 lol 2-3degrees is not worth 4hours of my time not to mention for less you could probably buy a second fan for that TRUE and get the same result.
MedicineBaby
Jan 23, 2009 6:07 PM
 I have heard of CPU lapping but never actually seen any results from it before nor knew of how it was done, but thanks for the guide Justin. I might try it on a cheap chip before I do it on my main one though XD

A question though Justin, what is the best drop in temperature you can get out of CPU lapping and what were your expectations when you first set out to lap the i7?
TheFrunj
Jan 23, 2009 9:24 PM
 LB: I'm sure you'll live :P

MB: The best drop you'd expect is up to ten degrees, with very shonky heatsinks and CPUs. The TRUE is already extremely good, lapping lesser heatsinks will give better increases :)
scruffy1
Jan 23, 2009 10:58 PM
 my only tip is using light machine oil instead of water to "wet" the surface

otherwise : yup, that's how you do it

nice guide
Xabbu
Jan 24, 2009 5:05 AM
 awesome guide mate :)
t8y
Jan 26, 2009 6:57 PM
 yep, did this about a month or two ago on my q6600 & TRUE120, plenty of youtube vids on the subject if you want to see it actually being done before you try it yourself..

i used an old mirror, and went 400-600-800-1200-1500. gave a good shine, and anything more is for e-peen lol

oh; i got a drop in the range of 10*C (load went from 78 to 68 @ 3.6), my TRUE had a rough, uneven surface (badly machined, and as it turned out was slightly higher in centre and one edge) and my cpus IHS was slightly higher on the corners and one edge - as these parts started to show copper much earlier than the rest of the surface.

recommended..
xtort
Jan 27, 2009 8:18 AM
 kerro is what we use at work for wet and dry paper has the added advantage of been non conductive. figuer eights are the best motion to use as the wear is even and can get it done a bit quicker. you can also use a marker to "blue" the surface that you are lapping and this will help you not to round the edges and stuff your cpu! it shouldnt take four hours maybe one or so
good guide though if you have NFI
I have done it and recomend it all the stuff is mass produced and only needs to be within the manufactures tolerances which could be anything up to .5mm out end to end
Jack Genders
Jan 27, 2009 9:14 AM
 Done this to my TRUE, not sure if I'd trust myself on the CPU though. Brave of you to give it ago, I can't magically pull the $$$ out of a new CPU if it goes wrong.
Jeruselem
Jan 27, 2009 2:15 PM
 Intel support folks must be cringing when they see this!
Hawkeye
Jan 27, 2009 2:52 PM
 Enthusiast: Oh, hi, is this Intel Support?

Intel Support: Yes it is, how can I help you?

E: Well, I lapped my CPU and -

IS: DEAR MOTHER OF GOD, WHY?!?!?!

E: Hello? Uh, is there anyone there?
nesquick
Jan 27, 2009 6:20 PM
 lol David, although I think it would be more like:

Enthusiast: Oh, hi, is this Intel Support?

Intel Support: Yes it is, how can I help you?

E: Well, I lapped my CPU and -

IS: uhh..... whats lapping? whats a cpu? is that the box thing?

E: palm face *pause* Just forget it.
orcone
Feb 2, 2009 3:06 PM
 Why exactly are you using glass?

That was never made clear.
LOL GLASS CLEAR I AM COMEDY
osama_bin_athlon
Feb 3, 2009 10:17 AM
 why not just remove the IHS?
osama_bin_athlon
Feb 3, 2009 10:19 AM
 er, you use glass for a perfectly flat surface to work with/on
;P
marvin_aus
Feb 9, 2009 3:01 PM
 orcone, google on how a mirror or any form of flat glass is made. it's a pretty cool process
Kimmo
Feb 12, 2009 2:00 AM
 If you CBF faffing about with wet-and-dry, reasonable results can be obtained by scraping a fresh snap-blade across the surfaces in question...
Lale
Feb 21, 2009 11:35 AM
 The purpose of CPU lapping is just to make the surface flat. There might be a better way...use LIQUID METAL to fill the gap between heatsink and IHS coz liquid would be flowing to anywhere any gap. Check http://www.jecca.com.au/products/1096-010-001.htm
jack101
Apr 18, 2009 11:35 PM
 Not worth the 2 degree drop for losing your warrenty
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