about lapping my P4 2.6C cpu

kgs

Junior Member
Dec 28, 2003
11
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about lapping my P4 2.6C cpu (its attached metal enclosure to be exact)

I have read a half dozen articles about cpu lapping, and because nearly all of them say you can drop cpu temp by 5 deg Celcius, it seems like the thing to do. That is, I believe, if it is simple to achieve an effective result, and I suggest that it is, and a proper/recommended procedure is followed, if you want to do it, why not, the result is beneficial. I am assuming the following:

please indicate right/wrong/missing info (on every detail please) - I am tired of pointing out where I may myself be ignorant: or more or less, just go ahead and get that 5 deg. C out?

I have:
400 grit wet/dry sandpaper
600 grit wet/dry sandpaper
1000 grit wet/dry sandpaper
1500 grit wet/dry sandpaper
2000 grit wet/dry sandpaper
3m rubbing compound ("Fine Cut....Safely and effectively removes 1500 grit or finer scratches")

First I will photocopy the printed information on the outer surface of the attached metal enclosure with my Lexmark 5150 MFD. I hope this will not damage the encased cpu. Someone else did this to show the effects of the the various abrasive steps. Could it hurt?

Then I will pull out my sheet of glass. What makes me sick about this procedure at this point is this. I have several pieces of glass: some are thick and beveled, but quite old; some much never and thinner; some are mirrors; and I could even possibly purchase a brand-new mirror or two for showing off the complete pc mod I am undergoing from behind and below. I have heard that glass flows. Do I need to be at all wary of this fact?

I plan to use water and the green dishwashing liquid (Palmolive?); but not oil, because it is designed not to burn off, and may seriously affect the mating surfaces ability to transfer heat. Please comment if this is true also of the usage of any dishwashing liquid (i.e. should I just use water). The dishwashing liquid may offer a lubricating property?

Should I skip the 400 grit wet/dry sandpaper because it may be too coarse. What pattern of hand/chip movement should I follow? diagonal, circular, random, linear?

The rubbing compound is itself a liquid solute\solution or suspension, or whatever, and therefore may not desirable to use. I wanted a bottle anyways, but the impetus was that I have seen cpu lapping kits sold at specailty computer stores which include a rubbing compound, and the fine sand papers. I cannot say what type of compound is included. My own bottle's directions are for paint, and it says to use a clean, soft, cotton terry cloth. It does not say anything about adding water to the cloth. It says to apply in a firm, circular motion, by hand. I have no idea about whether to modify the cloth type, or whether to try to place it on the flat surface, of if ther abrasive action is so minimal that I can use my fingers.

I plan on holding the chip with by embedding it into a small piece of sytrofoam-like sheet. I have a few thicknesses and colours of possibly differning materials. I'm not sure if what I have is safe, only because I have read to use a non-conducting (or whatever type). I don't know if I can even puncture the stuff with the pins yet. I just garbage -picked the stuff. Should I get a specific style/material/thickness?

May I even grasp the thing with bare fingers?

I have no idea if I should use a cleaner to clean the surface after using the rubbing compound, or for that matter after the paper and water, or paper/water/dishwashing liquid procedure.

Do I have to worry about crap getting around the sides, or through the alignment hole. Should I plug the hole with a dowel or something, and does it need clearance so as not to affect the san ding alignment?

The cpu cooler I buy, I understand, will not need any work, as it comes as flat as a baby's bum.

The stock Intel heatsink and fan will be discarded, and since the mobo will have never seen any usage without it's aftermarket final cooling solution, the thermal pad, or wax, or whatever, will never have to be removed, and ANY possible residue on the cpu's attached metal enclosure will be removed by the lapping.

Is there any potential inaccuracy caused by this procedure regarding paralellism; or clamping force required by mobo/cpu?

Is it conceivable the I need to worry about actually sanding through the cpu's attached metal enclosure? I understand it is copper underneath.
 

Sheriff

Golden Member
Mar 14, 2001
1,182
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5C less is exteme IMO but if you must lap then just get a flat peice of glass and go from 600 to 1500 till silky smooth as that's the goal and then ISO alcohol it to clean.
 

Soulkeeper

Diamond Member
Nov 23, 2001
6,732
155
106
i just run my P4 without the IHS and use an already pretty well finished heatsink
no problem here

the IHS would prob be a larger problem if heat is really what is killing your overclocks


long post so disregard this post if i didn't take anything into consideration


also i usually use two different grits of wet sand paper and use a flat surface like a thick peice of glass to keep the sand flat
it's best to start off with something kinda ruff then go to 600 grit if you want
no need to use more than 3 grits of sand paper unless it is really bad


good luck
 

BugsBunny1078

Banned
Jan 11, 2004
910
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you're talking about lapping the Heat Spreader piece of metal on top of the chip . That is useless.
Remove the heat Spreader and then if you want to lap the core then do that but don't lap the heat spreader unless it is marred or something.