Lapping my QX6700!

I

invalidbuffalo

Limp Gawd
Joined
Apr 19, 2007
Messages
419
I have decided to lap the IHS on my QX6700. I just got sandpaper at autozone and a glass sheet at home depot.

wetsandyayhd7.jpg


Before:
beforelapad2.jpg


sandingub9.jpg


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stage2rm1.jpg


stage3tc7.jpg


After:
afterwetsandit9.jpg


wetsandreflectaw4.jpg


Hmm. Not the results I was hoping for :( ... I used 1500 grit though, so I wonder if I should go higher. Any suggestions?
 
...never lapped anything, personally. What's the glass for? Any temp differences before and after?
 
There's no point to going higher grit unless you just like the looks of it. The point of lapping is to flatten the often concave IHS on these chips. You will see no difference between a flat scratchy/dull finish and a flat shiny finish in terms of heat dissipation.
 
cool...

aren't you afraid of damaging the processor?


good job!
 
I'm pretty sure polishing it defeats the purpose of lapping it.
 
Sloth said:
I'm pretty sure polishing it defeats the purpose of lapping it.
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True. Before using this chip, he needs to clean the surface w/ denatured alcohol and a lint free cloth.

No need for brasso on a lapped processor.
 
calebb said:
negative.
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Everybody is concerned with nice shiny things, the purpose of lapping is flatness, ie good contact between surfaces which makes the heat transfer process more efficient. Having something nice and shiny is a sometimes a by product of flatness but not necessarily so. If its flat, and there is flat and then there is flat but you would never be able to tell the difference with a naked eye.
 
mito said:
cool...

aren't you afraid of damaging the processor?


good job!
Click to expand...

As long as I let it dry thoroughly and I don't sand the IHS down to the die it should be fine, right?

RoBo said:
Did you bend any pins? :p
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Nope :p

Proxy said:
Temps?
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I've decided to take the opportunity (while I had things out) to finish installing my water cooling. I won't have results until i finish.
 
You shouldn't have polished it, that will only hurt your temps. And why would it need to dry? All you have to do is sand, then wash it with alcohol, no water involved.
 
firewolf said:
You shouldn't have polished it, that will only hurt your temps. And why would it need to dry? All you have to do is sand, then wash it with alcohol, no water involved.
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Arent you supposed to wet the sand paper first?
Seems to be the consensus.
 
firewolf said:
You shouldn't have polished it, that will only hurt your temps. And why would it need to dry? All you have to do is sand, then wash it with alcohol, no water involved.
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I have heard the same thing, but often wondered if its true....
I would assume that the polish would get in the tiny "pores" and interfere with the thermal compound.
 
Isn't there a little hole where the IHS is? Wouldn't water and metal particles get stuck in there and possibly do some harm?

That's my main concern, or else I'd lap my IHS also. I did this back in the Celeron 366 -> 550 overclock days :D

Has any tried taking off the IHS with an exacto knife?
 
the IHS is soldered to the core on c2d I believe. Not much temperature difference from lapping from what i've read (most is 1 to 3*C), it's really a waste of time and you will be at risk of rendering the chip inoperable. manufacturers would have lapped the chips on the production line if it would make a significant temperature difference, that is why we have thermal paste.
 
hardc0re said:
the IHS is soldered to the core on c2d I believe. Not much temperature difference from lapping from what i've read (most is 1 to 3*C), it's really a waste of time and you will be at risk of rendering the chip inoperable. manufacturers would have lapped the chips on the production line if it would make a significant temperature difference, that is why we have thermal paste.
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I've read 5C for lapping just the CPU, 5C for just lapping the HSF (thermalright extreme) and 8C for doing both.

Someone did the test here, but I can't find the thread with search being down.

Just put a razorblade on either the IHS or HSF, corner to corner and marvel at the 2mm+ depression in the center of both :)
 
firewolf said:
You shouldn't have polished it, that will only hurt your temps. And why would it need to dry? All you have to do is sand, then wash it with alcohol, no water involved.
Click to expand...

Any residual alcohol that is not readily exposed to air needs longer time to evaporate hence the air drying.
 
popgoestheweasel said:
Everybody is concerned with nice shiny things, the purpose of lapping is flatness, ie good contact between surfaces which makes the heat transfer process more efficient. Having something nice and shiny is a sometimes a by product of flatness but not necessarily so. If its flat, and there is flat and then there is flat but you would never be able to tell the difference with a naked eye.
Click to expand...


Rough = not flat

Little grooves on both sides of the interface will be filled by either thermal paste or air. Preferably thermal paste. Both have vastly worse conductivity than copper. The smoother the copper surface, the shinier it will look.
 
polishing = good = flat.

Wet sanding is needed, water is used. I would have gone beyond 1500 grit though when sanding, probably up to 4000 at least for me.
 
jvrobert said:
There's no point to going higher grit unless you just like the looks of it. The point of lapping is to flatten the often concave IHS on these chips. You will see no difference between a flat scratchy/dull finish and a flat shiny finish in terms of heat dissipation.
Click to expand...

Could someone verify that this is true? You'd think that since direct metal contact is superior to the space filled by the thermal paste, that smooth would be better than rough.

Also, I thought the second point of lapping was to get to the copper which is a superior heat conductor to the nickel or whatever the top of the heatspreader is made of (?)

Now I'm all confused about lapping all over again :confused:
 
HarkovAdm said:
Could someone verify that this is true? You'd think that since direct metal contact is superior to the space filled by the thermal paste, that smooth would be better than rough.

Also, I thought the second point of lapping was to get to the copper which is a superior heat conductor to the nickel or whatever the top of the heatspreader is made of (?)

Now I'm all confused about lapping all over again :confused:
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I don't know about you but i like to get the best looking surface after i've invested 3+ hours in lapping so higher grit is just like the icing on the cake for me.

I see no harm in not doing it especially if theres a chance of cooling the cpu even more ; which is really why we lap in the first place.
 
Depends. Whether you are using a chemical to enhance the shine or are you using a finer grit paper to do so. I would personally use a finer grit paper just to eliminate the fact that a particular chemical would interfere with the thermal conductivity.
 
You DON'T need to polish it unless you want to be cool. There's nothing wrong with using a high grit sandpaper or fine steel wool for finishing but using a buffing compound is stupid. A mirror finish isn't needed. You're going to want to rub that down with alcohol before you put the thermal grease on it anyways.
 
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