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Lapping

D

dtess17

2[H]4U
Joined
Feb 7, 2005
Messages
2,235
I've heard a few people talk about lapping and how it improves their temps.
So my general questions are what is it?
How is it done ?
Is it safe ? (can it be overdone or can it cause problems?)
How much does it help with temps?
where can i get the materials ?

Thanks.
 
dtess17 said:
I've heard a few people talk about lapping and how it improves their temps.
1. So my general questions are what is it?
How is it done ?
2. Is it safe ? (can it be overdone or can it cause problems?)
3. How much does it help with temps?
4. where can i get the materials ?

Thanks.
Click to expand...
1. most heat sinks/water blocks/cpus/cpu heat spreaders are concave or convex and verry rough surface, lapping is sanding them with the sand paper on a flat surface(glass or a mirror is usualy used) to get a extremely flat smooth surface if you do it right
2. if you fuck up no ammount of as5 will save you, just make sure you do it ontop of somthing really flat
3. i got 5C lower doing heat sink, another 4C doing the cpu
4. walmart, 800-2000 grit, dont go to hardware, you find it in automotive where all there paints are about $20 covers you pretty much forever for lapping

process is this: you start with 800 grit and sand with water to make sure the sand paper wont clog once you got it really flat with the 800(it can take a long time, coloring with a sharpie can help hilight where you havent gotten it completely flat when you dont have a metal thats nickle/magnesium plated) if you do the 800 grit well the rest will be easy, from there step up to 1000 grit sand until it feels like the sand paper isnt digging in anymore, from there step up to as high as you want, eventualy from making it so smooth it will be just like a mirror as a side effect

if you want to speed things up you can start with 320 grit to get rid of the plating but you will get better results not rushing it, let the cpu/heat sinks weight sand itself, do not press down at all
 
ryuji said:
3. i got 5C lower doing heat sink, another 4C doing the cpu
Click to expand...

this might be a dumb question, but you really sanded down your cpu? the actual chip? I might be reading this wrong.... :confused:
 
nealio said:
this might be a dumb question, but you really sanded down your cpu? the actual chip? I might be reading this wrong.... :confused:
Click to expand...

most processors come with a integrated heat spreader. They can be lapped or removed to get better temperatures. I've even seen some people lap the actual cores, but this is much riskier.
 
ryuji said:
3. i got 5C lower doing heat sink, another 4C doing the cpu
Click to expand...

good answers. I would not expect to get 9 degree temperature drops though, as this is an extraordinary result. Just lapping the heatsink MIGHT get you a degree or two depending on how bad the surfance and contact with the processor is.
 
govtcheez said:
most processors come with a integrated heat spreader. They can be lapped or removed to get better temperatures. I've even seen some people lap the actual cores, but this is much riskier.
Click to expand...

3500+ Venice, does that have a heat spreader on it?

I have a koolance water block that was pretty flat as stock, but 7-9degs, thats something to think about.

and how do you know how much to take off?
 
govtcheez said:
$17 shipped. You may be able to get all the parts cheaper, but it's not a bad deal.
Click to expand...

You are probably right. Have to admit the only reason I used the kit is because Dave sent
it free for me to review.

The premium kit is a good option for the n00b - saves having to search around.
And the results are pretty good.
 
nealio said:
3500+ Venice, does that have a heat spreader on it?

I have a koolance water block that was pretty flat as stock, but 7-9degs, thats something to think about.

and how do you know how much to take off?
Click to expand...

Yes. All the A64 chips (other than DTR notebook processors) have a heat spreader on it. What you see on the chip with all the numbers and letters...that's it.

If your waterblock does not need to be lapped, then don't do it. You can do more bad than good if you don't do it right. If it's flat and looks shiney, then it probably doesn't need it. If it has lots of visible grooves and looks milled, then you might want to spend a few hours and get a mirror like shine to it.
 
govtcheez said:
Yes. All the A64 chips (other than DTR notebook processors) have a heat spreader on it. What you see on the chip with all the numbers and letters...that's it.

If your waterblock does not need to be lapped, then don't do it. You can do more bad than good if you don't do it right. If it's flat and looks shiney, then it probably doesn't need it. If it has lots of visible grooves and looks milled, then you might want to spend a few hours and get a mirror like shine to it.
Click to expand...


thanks for the help, yeah the block its self was mirrored, so I didn't do it, but I wasn't sure about lapping the processor... seemed kinda risky to me, I mean, you do want to h20 sand it right? getting all that crap all over the processor justs seems crazy to me, the last thing I want to do is ruin a good processor for a 4-3C drop.
 
mirror isnt the same as flat, i lapped my mirrored xp-120 and got better temps, just dont remember how much

lapping cores isnt exactly risky, the part you see ontop is far away from the actual processing core, you just want to take it easy and not give the die un-neccisary stress(sand with 1500 grit and higher only pretty much)


thats the level i lapp my cpu and water block to, i tried running it with no TIM at all and only got 5 degs C higher temps compared to baked on as5
 
Ok so lapping is just sanding down the base of a HSF.
Could a tool be used like a real sander or must this be done by hand?

I looked at the kit mentioned and says it contains a piece of glass, so am i right to assume that i would i lay the glass down put the sandpaper on that and then just repeatly run the heatsink back and forth on the sandpaper ?

How do i know when to switch to the next level of sandpaper ?
Is it possible to over due it ?

Thanks again
 
remember to wet the sand paper, you will know when to switch to next grit because it will feel different, unless your purposly gong farther then it is at that point, you switch to higher and then higher remember the purpose is to get it flat and smooth, not just smooth, smooth does little alone, it needs to be flat as well thats why i suggested coloring it with a sharpie so you can see the progress, only caveat to that is water will wash the sharpie off so you would have to check your work with the sand paper dry
 
> "Ok so lapping is just sanding down the base of a HSF.
Could a tool be used like a real sander or must this be done by hand?" <

A power sander wouldn't be a good idea if you want it flat. Best to do it by hand so you
can pay attention to details.

> "I looked at the kit mentioned and says it contains a piece of glass, so am i right to assume that i would i lay the glass down put the sandpaper on that and then just repeatly run the heatsink back and forth on the sandpaper ?" <

You are correct.

> "How do i know when to switch to the next level of sandpaper ?
Is it possible to over due it ?" <

Idealy you want to lapp just enough to remove ALL the marks from the previous more course
grit. After a while you get a feel for what is enough.
Be sure to clean everything with water OFTEN to remove any stray particles. Very important when changing grits.

Check out the instructions at the bottom of that premium kit page I lynked above. Way better than
some of the other so called "lapping guides" I've seen.
 
ryuji said:
mirror isnt the same as flat, i lapped my mirrored xp-120 and got better temps, just dont remember how much

lapping cores isnt exactly risky, the part you see ontop is far away from the actual processing core, you just want to take it easy and not give the die un-neccisary stress(sand with 1500 grit and higher only pretty much)


thats the level i lapp my cpu and water block to, i tried running it with no TIM at all and only got 5 degs C higher temps compared to baked on as5
Click to expand...

did you wet sand that?

do the particals/dust get into the way of the pins?

and how did you clean it after it was done?

thanks for the help bro, thats tight :D
 
ryuji said:
mirror isnt the same as flat, i lapped my mirrored xp-120 and got better temps, just dont remember how much

lapping cores isnt exactly risky, the part you see ontop is far away from the actual processing core, you just want to take it easy and not give the die un-neccisary stress(sand with 1500 grit and higher only pretty much)


thats the level i lapp my cpu and water block to, i tried running it with no TIM at all and only got 5 degs C higher temps compared to baked on as5
Click to expand...


That looks pretty amazing bro. I didn't even know you could lap the actual CPU die until I read this thread.
 
lots of time(if your noob, took me about 20 minutes total but i have done many many heat sinks, some many times because the athlon-xp core was prone to leaving dents in the heat sink) and sand paper of all grits
 
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