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CPU Lapping

furnace

furnace

furnace

Soldato
Joined
12 Dec 2006
Posts
3,421
Location
Worthing, West Sussex
I've discovered that my E6300 is concave! So I guess I need to lap it. I have a few questions about it, for anyone who has experience with lapping.. If you can advise me with any of this then please do :D

Right, this is a paint drawing of my problem
ciphsfrt6.jpg


The gap, in reality, is really small. But I guess it's enough to make a big difference - my heatsink's base is at least 15'c cooler than the core temp - sometimes even 25'c cooler, so this would explain why! I would only expect a 5'c, MAYBE 10'c, difference between the core and the heatsink.

Would you agree that this is my problem? I idle at 57'c where others are idling at 35'c on the same processor.

Can you give me advice on lapping?

Is it worth lapping and voiding the warranty?

From what I've read, you get a little bit of oil and drop it onto each piece of sandpaper you use. First, you use 400 grain, then 800 grain, then 1500 grain, then 2000 grain. When doing it, you put the processor IHS-down onto the sandpaper, which should be on a pane of glass. Then you move the processor in small circles applying gentle force.

How long should I do it on each size grain sandpaper? I guess longer with the 2000 than the 400?

Thanks for any advice or warnings :)
 
Lapping will void your warranty, but in the case of Conroes, if you're overclocking, is very worth doing as they can be very concave. It's dropped my load temps on a E6600 by about 15C. The effect was so dramatic that I did to my QX6700 without even both checking what temperatures it would hit without it.

When I did it, I used 200, 400, 600, 800, 1200, 1600, and finally 2000, each for about 3-5mins, using wet (with water) paper on a sheet of glass. Then to finish off I polish the top with Brasso for a minute just to give it a mirror finish.

Jokester
 
Jokester said:
Lapping will void your warranty, but in the case of Conroes, if you're overclocking, is very worth doing as they can be very concave. It's dropped my load temps on a E6600 by about 15C. The effect was so dramatic that I did to my QX6700 without even both checking what temperatures it would hit without it.

When I did it, I used 200, 400, 600, 800, 1200, 1600, and finally 2000, each for about 3-5mins, using wet (with water) paper on a sheet of glass. Then to finish off I polish the top with Brasso for a minute just to give it a mirror finish.

Jokester
Click to expand...

I did exactly the same as Jokester and saw a drop of 9 degrees using 400,800,1200 and 1600, didnt bother with the brasso though. ;)
 
At the moment I'm getting 48'c idle @ 2.1Ghz on an E6300, and 65'c full load :( A 15'c drop would be VERY appreciated! *crosses fingers*

I've emailed intel about it (quoting stock speed temps though, which are 46'c->57'c) and I'll see if they reply with anything worthwhile. E.g. the offer of a replacement.

But, tbh, tomorrow I think I will be lapping the processor.

Can you get those sandpaper's from B&Q and any other hardware store?

Also, you do it with the processor face-down on sandpaper... how do you move the processor around whilst keeping a bit of force on it without touching the pins?

Cheers :)

Zefan said:
Are you sure it's not your heatsink that's out of shape? Just making sure.
Click to expand...
Yeah, before hand I checked the heatsink with the edge of a metal ruler and bright light and it was fine. Then I checked the processor with the edge of the metal ruler and noticed it, then used the heatsink just to confirm they weren't properly contacting each other (wudda been great if the heatsink was convex and the processor concave, eh! lol). :cool:

touch said:
just out of interest, how can you tell its concave?
Click to expand...
Concave, is like a flat surface with a dip in it. Convex is the opposite, so it'd be a flat surface with a bump on it. If it were convex, I would be able to make the two wobble against each other slightly :)
 
furnace said:
Also, you do it with the processor face-down on sandpaper... how do you move the processor around whilst keeping a bit of force on it without touching the pins?
Click to expand...

Just hold it by the edge, 775 chips don't have pins on the chip.

I bought mine from a model shop, but it seems that your local autoparts store might have the right grits. As far as I can tell B&Q don't have that fine a paper.

Jokester
 
Jokester said:
Just hold it by the edge, 775 chips don't have pins on the chip.

I bought mine from a model shop, but it seems that your local autoparts store might have the right grits. As far as I can tell B&Q don't have that fine a paper.

Jokester
Click to expand...
Chips, blobs, whatever... :p hehe

Thanks for the advice, I will pop into B&Q tomorrow to get what I can, then I'll go to the model shop and see if they have what I need.

If you think of anything else I should know please tell me - this feels quite a daunting task and don't wanna go wrong anywhere! :D

Halfords might ..? What would you want paper that fine for on a car? Smoothing surfaces for painting? (just so I know whereabouts to look in store)
 
Jokester said:
Lapping will void your warranty, but in the case of Conroes, if you're overclocking, is very worth doing as they can be very concave. It's dropped my load temps on a E6600 by about 15C. The effect was so dramatic that I did to my QX6700 without even both checking what temperatures it would hit without it.

When I did it, I used 200, 400, 600, 800, 1200, 1600, and finally 2000, each for about 3-5mins, using wet (with water) paper on a sheet of glass. Then to finish off I polish the top with Brasso for a minute just to give it a mirror finish.

Jokester
Click to expand...

You shouldn't use anything to polish the god damn thing, as most/all polish products leave a wax residue. This is to avoid oxidation, but you do not want it between the cpu and the heatsink.

Also, please don't forget:
flatness > shiny

;)
 
sablabra said:
You shouldn't use anything to polish the god damn thing, as most/all polish products leave a wax residue. This is to avoid oxidation, but you do not want it between the cpu and the heatsink.

Also, please don't forget:
flatness > shiny

;)
Click to expand...

Which is the entire point of lapping ;)

Brasso isn't a wax based polish.

Jokester
 
sablabra said:
Also, please don't forget:
flatness > shiny

;)
Click to expand...

Yes it is thats why you should get it flat using paper, then polish it.
Finally you should always clean the surface with your normal cpu cleaner before applying the thermal compound, removing any waxy residues left behind.
 
Pretty dumb that lapping can void your warranty when you think about it, if the heatspreader was perfectly flat then there'd be no point, if its not then the heatsink isn't getting a good contact which can lead to the cpu being unstable. Think intel and amd in future need to give us flatter heatspreaders, this concave thing is obviously a flaw on their end.
 
Jokester said:
Have a look in here on how to test how flat it is.

Jokester
Click to expand...
Using that, my heatsink seems pretty flat - although I can't see how I'd lap it without taking the "legs" off it. Either that or I'd need a pretty small pane of glass. But yeah, hopefully that won't really need lapping just cleaning up a bit.

The CPU, I used the optical thingymajig and the very corners of the IHS make the lines wobble, so I guess that's the raised edges doing that..!

Well I'm gonna go pop out to halfords and see what they got in a second (edit: wtf, i swear halfords shut at 8... that was a waste of petrol). I might do it tonight as i'm pretty awake and have nothing better to do.

Although I've emailed intel about it, maybe I should wait for their reply? But tbh as it's under 65'c at stock speeds they'll probably tell me it's fine :mad:

Another question; why should I make the paper wet? What difference does it make?
 
Last edited:
furnace said:
Although I've emailed intel about it, maybe I should wait for their reply? But tbh as it's under 65'c at stock speeds they'll probably tell me it's fine :mad:
Click to expand...

Dont tell them your using a diffrent cooler that also voids your warranty,I made the mistake in telling them but the Intel guy said he would let me off. :)
 
You use water to lubricate the contact area and also to prevent fine particles of dust entering the atmosphere, and as were are talking metal particles you don't want them lodging on the smd's on the underside of the cpu tbh.
Gonna do mine next week. Most auto/diy stores stock upto 1200 grit, model shops are a better bet for finer stuff although you only really need finer stuff for looks. A dull finish without any visible scatches is better imo as thermal compound can then fill the microscopic grooves rather than lying on the surface and acting as an insulant.

Heres my storm I did recently which I reluctantly had to lap due to the scratches in it.

Before :
Picture019.jpg


After

Picture024.jpg


Lapped upto 1500 then cleaned with IAP. I would have gone further but I didn't have any 2000 and tbh it would only have been for looks which no-one would see anyway lol.

Shiny is nice but no extra benifit in cooling.
 
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