Lapping Your Processor For Fun and Profit!

So, I realized the other day my i7 is WAYYYY too hot. Like idles at 50 hot. So, being the intrepid soul I am, I decided to check its flatness. Warning:pics can be scary. Do not allow children under 18 to view.

You can see here the processor is actually proud in the center...

And that it extends all the way across in one direction. Machine skipped?

So, I've applied TIM to get a footprint test-it's not the normal way to check, but it gives better results than anything else I know. Sorry, Lumiere...

And here's the lapping glass in place. Not only is it perfectly flat, but it weighs as much as the average aftermarket heatsink, as well. Note the thick bond, air is squeezed out but there's too much TIM in the center-it's sitting around that crown.

Still, the TIM joint is far too thick-the glass rests on the high spot.

In this shot, the fractal pattern around the center indicates the area of greatest contact-in the center only. It's interesting to note the amount of area that never made contact...

So what's a guy to do? Lap, of course. We'll get rid of that high spot in no time flat. (Pun intended.)

Our tools assembled, we set to work. We have...

A CPU. If you're going to lap a CPU you kinda need one.

A sheet of glass. Mine is actually lapping glass, it's as flat as engineers can make it, but almost all glass is float glass today, which will be pretty much perfect.

Tape. I use 3M's top line stuff, but anything that pulls off clean will work.

And sandpaper. Once again, 3M, but be sure it's wet/dry sandpaper. You'll need to wet the processor to make sure the copper dust floats off instead of loads the paper.

Tape your paper to the glass. This will stop it from sliding around as much.

At this point, put a few drops of water down and start sanding. Also, you may wanna start a movie.

A few words on sandpapers and lapping-starting with 600 will remove metal fast, but you'll end up going through 800, 1000, 1500, and 2000 to get them out. As all I had was 1000 and 2000, it goes slow, but makes very flat CPUs anyway.

As you can see, the first area to lose metal is the center.

So reflective, it focused on the background...

Ready to move on...

And done. Took a few hours, a lot of elbow grease, and patience. But, as you can see, it looks much better.

Remember your processor is a sealed unit, and don't be afraid to put some water down or wash it clean. Both are important steps.

Questions, comments, flames, you know where to leave them. I have more testing to do.

what are the temps now?

What he said. /\

Also, I'm curious as to why it takes hours? I've never lapped a CPU but I've done my share of sanding and polishing, with wood acrylic and metal, and I can't figure why it would take that long. What am I missing? Are the IHS on a processor made of adamantium?

Very nice tutorial. Also interested in your temps now. Also, as a final touch I'd try undervolting.

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Originally Posted by blueonblack

What he said. /\

Also, I'm curious as to why it takes hours? I've never lapped a CPU but I've done my share of sanding and polishing, with wood acrylic and metal, and I can't figure why it would take that long. What am I missing? Are the IHS on a processor made of adamantium?

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from what ive read the hours part is due to the excruciatingly slow speed you have to lap at/how lightly you have to press to keep the surface even? also multiple grits have something to do too to make it as smooth as possible... Havnt had to lap a cpu either, but thats my educated guess

You got it in one. Little pressure, high grits and patience produce a VERY nice end product, lower grits and muscle can do much the same but the finish isn't the same. We're going for engineer-quality flatness, not pretty. I'll take the time to do it right rather than have temps be worse than they were before.

As to temps, I'm still sorting things with the cooler I'm reviewing. The cooler may well be bad, as well. We've seen some inconsistencies thus far, and I'd like to investigate them further.

Hmmm, this makes me wonder about my own CPU...I haven't been able to pull its idle temps under the mid 50's, and with my cooling system there's no reason for that. I already lapped the block a while ago, I think while I have the system apart anyways that I'll go ahead an lap the CPU as well. I've just always been paranoid about it...it's a lot cheaper to replace a $50 block or HS/F than a $300 CPU.. /crosses fingers

x88x... just take it rly light man..... dont put any pressure on it.. period... let the weight of the cpu do its own work.... just move it back and forth

Nice job! Informative, entertaining, and well photo-documented.

I started getting nervous when I did my q6600 because I'd taken off so much metal that I decided to stop. Although it's flat, it doesn't look as good as this because I didn't get all the aluminum off. It's sort of an ugly swirl of the two colors even though it's an uninterrupted mirror finish. How thick is the typical IHS? The last thing I wanted to do was see silicon dust on the paper...:dead:
Anywho, this takes millions of strokes due to not putting any pressure on it. That's why it takes so long. It really depends on how untrue the IHS is in the first place. From online discussion and my own experience, 1-3 hours is pretty standard. Since Intel decided to get artistic and made my IHS in a wave-ripple pattern, mine took several hours as well.

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Originally Posted by mDust

Nice job! Informative, entertaining, and well photo-documented.

I started getting nervous when I did my q6600 because I'd taken off so much metal that I decided to stop. Although it's flat, it doesn't look as good as this because I didn't get all the aluminum off. It's sort of an ugly swirl of the two colors even though it's an uninterrupted mirror finish. How thick is the typical IHS? The last thing I wanted to do was see silicon dust on the paper...:dead:
Anywho, this takes millions of strokes due to not putting any pressure on it. That's why it takes so long. It really depends on how untrue the IHS is in the first place. From online discussion and my own experience, 1-3 hours is pretty standard. Since Intel decided to get artistic and made my IHS in a wave-ripple pattern, mine took several hours as well.

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about a the thickness of a dime, so you have plenty of metal to keep going.

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Originally Posted by Spawn-Inc

about a the thickness of a dime, so you have plenty of metal to keep going.

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Heh, I hold in my hand a dime. Upon examining it, I'm glad I stopped when I did. I actually took off a large amount of material with 400 grit getting the thing flat. It was disgustingly warped. The outside edges and center were about .5-1mm higher than the doughnut shaped depression. There's no way that the doughnut area was even in contact with my bowed HS. They're both flat now and the temps dropped significantly. Winter idle after the lapping was around 25-30C and summer seems to be 40-45C. Looks like it's averaging about 15C over ambient. All is well now.

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Originally Posted by mDust

Heh, I hold in my hand a dime. Upon examining it, I'm glad I stopped when I did. I actually took off a large amount of material with 400 grit getting the thing flat. It was disgustingly warped. The outside edges and center were about .5-1mm higher than the doughnut shaped depression. There's no way that the doughnut area was even in contact with my bowed HS. They're both flat now and the temps dropped significantly. Winter idle after the lapping was around 25-30C and summer seems to be 40-45C. Looks like it's averaging about 15C over ambient. All is well now.

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and you still had nickel left on the block? it's just a plating and should come right off within 10 minutes of 400 grit.

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Originally Posted by Spawn-Inc

and you still had nickel left on the block? it's just a plating and should come right off within 10 minutes of 400 grit.

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Like I said, it was crazy-warped. I stopped sanding with low grits as soon as my 'sharpie X' was completely gone. The 1000+ smoothed it all out without taking the nickel off. But the center bump and the outside perimeter lost a ton of copper. I wasn't sure how thick the IHS was so I called it good:

Its color looks ugly, but it's mostly flat and has a very nice mirror finish everywhere but the outer edges of the extremely low doughnut area:

The only real issue now is over core #0...it's not quite a mirror finish over about half of it...
I'm really not sure how Intel thought the shape of this IHS was OK to begin with, but hopefully my next CPU won't have such severe 'flatness' issues.

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Originally Posted by mDust

I'm really not sure how Intel thought the shape of this IHS was OK to begin with, but hopefully my next CPU won't have such severe 'flatness' issues.

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It probably falls under the 'it would cost us a lot more to actually make them all flat, and they're fine as-is for most of the population, so....eh'.

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Originally Posted by x88x

Hmmm, this makes me wonder about my own CPU...I haven't been able to pull its idle temps under the mid 50's, and with my cooling system there's no reason for that. I already lapped the block a while ago, I think while I have the system apart anyways that I'll go ahead an lap the CPU as well. I've just always been paranoid about it...it's a lot cheaper to replace a $50 block or HS/F than a $300 CPU.. /crosses fingers

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this makes me wonder the same thing about mine...but...it'd be such a pain to get to it I probably won't worry about it. idle is low 40's anyway, which for the fans I have to use I think is pretty good (6 scythe slipstream 1.2cm thick sandwiching the rad instead of the standard 2.5cm thick).

Still, thanks for the tutorial, it's nice to know how to do it properly! :up:

lol... looking at the way the intel ish are made is kind of strange.... the AMD design looks like its easier to keep flat... just my observation...

I'll be doing this once my new board come in from Trace (well that and I get Project Tempest SXR done to put this HW in)

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Originally Posted by diluzio91

lol... looking at the way the intel ish are made is kind of strange.... the AMD design looks like its easier to keep flat... just my observation...

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ya there covers seem to be very flat, though i've never tested any.


as for the OP the sharpie test is kind of useless IMO as it's gone in 5 passes or so.

I've followed this guy's on his older version.
http://metku.net/index.html?path=mods/lapping/index_eng

You should try the polish. :)

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Originally Posted by Spawn-Inc

as for the OP the sharpie test is kind of useless IMO as it's gone in 5 passes or so.

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I mentioned using a 'sharpie x', not Kayin. If you think it's useless then you must not have experienced an Intel IHS!:D

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Originally Posted by Collinstheclown

You should try the polish.

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If you use polish then it might look too good to cover up with a heatsink!

I thought i'd try this out for kicks. I have a couple old celeron single core proc's laying around that i dont have a use for. Perfect! I scavanged some glass from a candle holder lantern thing, grabed some 240, 400, 600 grit dry paper and went to town. I wasnt peticularily worried if i messed up so i did a super fast job, about 40 min total. I started with the 400 just to see how it would go. It was taking forever so i went to the 240 and started really hauling on it. When the aluminum top coat was removed and the surface started to flaten out the concave surface and became smooth, i switched to the 400 grit and started to haul away on it some more. Went to 600. Then i had a stupid idea. I thought i'd try some polishing compound on the glass the same as i did the paper. That made a mess and i had to restart at 400 to fix the big scratches it put in it. All's well that ends well i guess. Exceptional quality surface and i managed to not bend a single pin.

I could have gone to a further grit paper and or a buffing wheel on a grinder to get it to a mirror finish but its not worth the money i'd have to spend on the sand paper. I think it's a pretty damn good improvment over what it was like before :)

I took pic's of the whole operation but imageshack is being a whore today and is going at a snails pace. I'll upload the pics tomorrow afternoon when i get home from work.

[edit] Images were done faster than i thought.

I made sure to copy the specs and serials just incase

Awesome tutorial, I feel confident now that i could attempt this on a much more expencive processor.

A+++

A while ago I picked up a pack of two sheets each of 300, 400, 600, 800, 1000, 1500, 2000, and 2500 grit off ebay for ~$10, iirc. It's lasted me several years and I haven't even touched the second set of paper.

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Originally Posted by CanaBalistic

Awesome tutorial, I feel confident now that i could attempt this on a much more expencive processor.

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You've got the technique down, but if you do lap a more expensive processor, make sure you use much higher grit papers. Those lower grit papers work faster because they tear larger gaps through the metal...this is bad for perfectly mating two surfaces, which is the goal here. I'd recommend at least 1500-2000 grit to finish, with higher grits and polishing compound being optional.

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Originally Posted by x88x

It's lasted me several years and I haven't even touched the second set of paper.

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Haha, you have to sand stuff with the paper to use it up. If you don't, technically it does last forever!:D Though, I've found that wetting the paper and then keeping it clean makes it last a very long time.

If you use a polishing compound, be sure to use a degreaser to get all the residue out. It's really nasty and won't break down with just water. Lapping compound not removed can leave temperatures just as bad as unlapped because the TIM has to sit on top of non thermally conductive lapping compound.

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Originally Posted by mDust

Haha, you have to sand stuff with the paper to use it up. If you don't, technically it does last forever!:D Though, I've found that wetting the paper and then keeping it clean makes it last a very long time.

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:P

Perhaps I should have said, I'm still using the first set several years later. Some of the sheets are nearing the end of their life, but I've lapped, iirc, 3 waterblocks, 1 CPU, and 1 heatsink with them. Only the 400 and 600 are really showing any wear.