To Lap or Not To Lap.

[Miles]

Well, I must confess. I've never lapped before but I'd like to! I can see how to sand the hs/f but I can't visualize how to keep the cpu core perfectly flat during the lapping process. Is there a jig available? Please pass on your lapping prowess.

[Rick_Deadly]

Lapping a heatsink is a relatively safe process. Just place a sheet of sand paper on a flat surface and do figure eights on it with the heatsink. Grip the heatsink "over the top", and on all sides so you apply a "flat" even pressure. You do not want to round the edges. Start with a medium paper and then work up to a fine paper, using several grits in between. Remember, you are only working with soft aluminum or copper, so you don't need a lot of pressure.

Athlon and Duron CPU's do not have much of a coating on top of the core. Personally I would not even try to lap one of these.

[dnar]

I agree. CPU's do not require much lapping if any at all. I recently lapped a GlobalWin HS, using very fine wet&dry and a peice of mirror. The HS was lapped in 3 stages, to acehive a mirror finish. The final results were a reduction of CPU temp by 2-3 degress C.





With the CPU core being so small, It is possible you actually round the edges off, thus making it worse. IMHO, just lapp the HS. (Dont forget to shut the puter off before doing this).... :rolleyes:

[MechCD]

I've read something about using a piece of lass to make sure its flat, bt I don't know if you put the sandpaper on the glas, or the heatsink on the glass.

Make sure you end up with higher than 600 grit

I saw a heatsink that was "lapped" with a very fine (cough) grit of 200 :eek:


to not confuse peeps, 200 grit is very rough. this fellow had actually made the finish worse

[dnar]

Originally posted by MechCD
I've read something about using a piece of lass to make sure its flat, bt I don't know if you put the sandpaper on the glas, or the heatsink on the glass.



Make sure you end up with higher than 600 grit



I saw a heatsink that was "lapped" with a very fine (cough) grit of 200 :eek:





to not confuse peeps, 200 grit is very rough. this fellow had actually made the finish worse
The gwet&dry is placed on the glass! I ended with 1200 grit....

[wbierman]

I lap both. I spend more time with the heatsink than I do with the CPU core. It does make a difference. When I pull a lapped HS off a lapped CPU, there is hardly any evidence of heat compound on the CPU surface.

If you pull a HS off a CPU and you can see lots of heat compound still on the CPU core.... you don't have good contact and that means lousy heat transfer.

The key to lapping a CPU core is to only apply pressure with a single finger to the center of the CPU die. They are much closer to flat than most HSs so they don't require as much lapping time.

I use automotive wet/dry paper in gritts above 800 with a drop or two of paint thinner as a lubricant.

The proof is in my temps... usually in the 34 - 36C range... all day long!

[MaTriX]

Originally posted by dnar

The gwet&dry is placed on the glass! I ended with 1200 grit....
That's my favorite, 1200 make it look just great too, a mirror...

[Miles]

One finger in the middle and a figure of eight patttern. Got it. Thanks!

[siggy]

OK I think I understand. This lap thing means I run around my computer. Right? But what am I lubricating? I am not clear on this part. Course I am not quite sure how running around my computer is going to cool it down. It is because it causes more air flow?

[pelligrini]

If you have one finger in the middle doing a figure of eight patttern, something ought to be lubricated. ;):D

[verT]

What is that something pelligrini, enlighten us:D

[wbierman]

Is that K-Y or paint thinner?

[MechCD]

Hehehehe


Don't lap the core, just don't

Unless you have one of those superhuge celeron dies............. or a pentium pro..... dang those ppros keep coming up out of nowhere!

[wbierman]

What is the point of lapping your HS if your CPU core in uneven?

An absolute waste of time... you have to do both to see a real benifit.

[MikeTimbers]

Originally posted by MechCD
I've read something about using a piece of lass to make sure its flat,

Depending on which piece of a lass you use, it could be very distracting :)

[dnar]

Originally posted by MikeTimbers







Depending on which piece of a lass you use, it could be very distracting :)

LOL! A lass on your lapp maybe???? :D

[siggy]

BAD Penguin!

[MechCD]

Originally posted by MikeTimbers




Depending on which piece of a lass you use, it could be very distracting :)

GLASS! der oops....

What imena is, you can ruin a Tbird or duron easily be lapping it. Or even a coppermine. Most of them are flat already. Lapping was done when those wonderfull celeron 300as were very concave and the heatsink made contact with like %40 of the slug. thats another point, the CPUs that peeps lapped, had SLUGS ON TOP od the dies so that when you lapped, you were only lapping the outer "shell" and not the silicon.

When you lap a duron or tbird, you are lapping the silicon or the glue they use to protect the die. Whats worth all the rist of oversanding or weakeneing the die? 1-2 degrees?

Go ahead and lap the heatsink, some of those are pretty bad.

another thing, watch what thermal grease you use. i thin artic silver is ridiculous.

Radioshack stuff works great. the stff int he blister packets is awful. I had a tbird running 160F idle with the stuff from a blister pack. I cleaned it off and put some RadioShack paste on ther and now its 130F load, 110F idle.

[Yo_Mama]

1200 is ok, but I go to 1500 & follow with 10,000 polishing compound I also use for clearcoat car finishes :)

Originally posted by MaTriX

That's my favorite, 1200 make it look just great too, a mirror...

[MechCD]

Why? Whos gonna see it? SOmetimes making it shiny also makes it uneven, it might LOOK flat.

Really guys, is 1-2 degrees worth the hour of lapping to mirror finish? I say lap the Heatsink if it is uneven or cruddy, but not he core (unless it has a SLUG)

Also, you want the two surfaces to stick, like 2 pieces of glass with a drop of water in between. If it doesn't sick, its not flat. Also try to use the least amount of grease you can, while still covering the areas that need to contact each other

[Yo_Mama]

Don't know why, actually.. Once I get to polishing, I just go nuts. :)

Originally posted by MechCD
Why? Whos gonna see it? SOmetimes making it shiny also makes it uneven, it might LOOK flat.

Really guys, is 1-2 degrees worth the hour of lapping to mirror finish? I say lap the Heatsink if it is uneven or cruddy, but not he core (unless it has a SLUG)

Also, you want the two surfaces to stick, like 2 pieces of glass with a drop of water in between. If it doesn't sick, its not flat. Also try to use the least amount of grease you can, while still covering the areas that need to contact each other