Lapping CPU?

[systemlord]

HI all, I wanted to know if its a good idea to lap a CPU before using it? What if its a DOA? I have lapped my Tuniq Tower 120 (can see my face in it) and I know that my CPU is Not flat, its high around the four corners/concaved. Am I overreacting or should I just do it? Thanks

 

[Assman]

wanted to know if its a good idea to lap a CPU before using it? What if its a DOA?

They rarely are, but you can build a system, make sure everything is working right and then lap.

 

[tomwaddle]

help a brotha out... what the hell is lapping?

 

[Assman]

help a brotha out... what the hell is lapping?

Polishing to a high sheen and flat surface, start out with large grit and work your way down, then finish up with polishing paste.

at the end it looks like this

 

[tomwaddle]

Seems like a lot to risk for a cooler temp.

 

[Assman]

no risk, just voiding the warranty

 

[tomwaddle]

I guess I wouldn't risk it to void the warranty. Especially if the cpu was one of the newer, $400+ cpu. Thanks for the lesson on lapping

 

[yadge]

Why don't amd and intel just make the heatspreaders flat to begin with? It can't be that much more expensive to do that. I guess it just takes too mcuh time for them.....

 

[systemlord]

To lap my HSF I used a thick piece of tempered glass then put some 800 grit with some water under the sandpaper so it won't move around. How thick is the heatspreader on the CPU? I am considering doing it...

 

[darious00777]

There would be difficulty in placing required information on the CPU if the chips came prelaped. All the identifiers would have to go on the underside. Quite a feat for AMD to accomplish, and for Intel chips, they'd have to be mighty creative to do it.

 

[Asjasck]

I lapped my notebook's P4 and temperature drop by few degrees only. Unless your CPU heatspreader is not leveled there shouldn't be a need to do it. But it takes time for a good lapping

 

[systemlord]

OMFG! LGA 775 I was pushing very softly to get me CPU into the socket and bent two pins! How do I bend them back? I thought I was to apply some pressure for it to go in? What do i do now?

 

[Assman]

try to bent them back with a needle or something small, be carefull though

 

[croc]

Your local plate glass replacement shop should be able to help out here, cheaply if you don't care about artery-slicing edges....

I like the water based grits, available at most good carpentry shops in grits from 800 to 5000.

Your piece of plate will need to be replaced often if you do this a lot, so become friends with your local glass shop. The grit can be dried and re-used several times with no ill effect. (that's why I like the water-based)

If using a cpu with pins, it is probably a good idea to use some conductive foam on the pin side of the CPU. Even with BGA chips its a good idea but will require some carefully applied tape to hold it in place better. I've heard of using aluminum foil, but I'm of the old school 'better safe than sorry'.

My 2p

 

[systemlord]

Does the CPU just rest onto the pins or does the CPU need to be push through the pins a little? Is there some place i can take my mobo to get them fix by someone that knows how to get the pins back?

 

[Assman]

you you're suppose to to gently put cpu on to the mobo socket, no force needed. i guess you can try to call any local pc store, compusa, bestbuy etc.

 

[nvalhalla]

Did you break them or bend them? If they are broken you are probably screwed. I'm sure even that COULD be fixed, but good luck with it. If you are REALLY lucky they may not be used, so I would plug it in and try it out, some of the pins aren't used for anything, it might still work... If they are bent then I would try, very carefully, to straighten them out with a needle.

 

[Assman]

he said he bent two pins, not break

 

[systemlord]

I was able to bend the pins back, but they aren't angled the same as the others so when i clamp it down with the lever are they going to bend down at the angle olike the others?

 

[Mondoman]

It's hard to know without photos. Try it and find out.

 

[systemlord]

I got the two pins bent to the right angle now, but one pin is just a little (I mean very little) shorter than the rest. Is it ok to have one pin a hair shorter than the rest?

 

[dasickninja]

I guess I wouldn't risk it to void the warranty. Especially if the cpu was one of the newer, $400+ cpu. Thanks for the lesson on lapping

Question, do you plan to overclock? Because that automatically voids the warranty. So if you plan to do such, might as well invest the time into lapping and please, I mean please, do not use Arctic Silver 5 on a lapped IHS.

 

[omgitslong]

why not? What's wrong with using AS5?

:idea:

 

[dasickninja]

Nothing is wrong with Arctic Silver per say, but think about it logically. AS5 is used to bridge the gap between the IHS and the heatsink base by filling in the microscopic ridges and grooves on the IHS and HSF. Lapping, when done at least partially correct smooths the surface of both the IHS and HSF, providing more surface area for heat to be dissipated from and removing the microscopic grooves which AS5 fills in.

Now when you lack those grooves and ridges on the surface AS5 only acts as a barrier, preventing proper heat flow and can in the end, cause higher than projected temperatures. That's why you don't use a silver or (most) metal based thermal goops when lapping and use silicon based goops which fill the area better than AS5 and the like.

There is a point when the lapping is done so well that you don't even use a TIM but none of us will ever reach that point.

AS5 is good for a stock surface. Other than that, it's being wasted.

 

[ajfink]

I got the two pins bent to the right angle now, but one pin is just a little (I mean very little) shorter than the rest. Is it ok to have one pin a hair shorter than the rest?

It could just be a grounding pin. Give it a shot.