lapping heatsinks

[iceman7311]

I recently read a article and found out there is a process called lapping a heatsink. i was just wondering of you all do this and if so what type of results you get.

 

[Sazar]

I typically buy Zalman heatsinks. They are typically pre-lapped and much smoother than anything I could hope to do so I don't bother.

My cpu and gpu both have pretty nice, smooth finishes for the copper base.

 

[lancer]

what is prelapping?

 

[Sazar]

They come with perfectly smooth finishes out the box, i.e. they don't have the grimy, un-finished base that some cheaper coolers do. My cpu heatsink had a mirror finish, the one for the gpu was less so but still a darn sight better than the stock AMD and ATI coolers.

Dull finishes typically require some sort of additional lapping to ensure the best contact and, as a consquence, the best performance.

 

[ElementalDragon]

pre-lapping = smoothed by the manufacturer. all coolers are Pre-lapped.... just some manufacturer's tend to do a better job than others.

 

[lancer]

so if it is lapped, so i still need to add paste or tape?

also i'm putting on a new cooler for my gpu, which has a mirror finish, if i do need to put paste on it, exactly how much should i apply?

 

[Sazar]

You always add paste, tape is for noobs.

You always add paste because no matter how smooth the finish, there will always be spaces and the paste fills it up.

I only ever use Arctic Silver 5 or better for my heatsinks. After it "cures" it does a really good job of cooling.

 

[lancer]

so exactly how much should i use for a gpu?

p.s. i never used paste for my amd 64 3200 and it idled at 24c

 

[iceman7311]

is there suck think as lapping the cpu? because the surface of amd 64 does nat have a mirrior finish and itis not that smooth.

And in theory one could make there heatsink and cpu so smooth that they would not need thermal paste?

 

[Sazar]

For Lancer, you typically just need a bead or so of the arctic silver. When you put the heatsink on, it should spread everything out nice and evenly.

For iceman, you would probably have to get some very fine sand-paper or something like that. Sanding is about the only thing I can think of, else just get a different heatsink. The Zalmand coolers for the cpu's consistently have a lovely mirror finish. And no, you will always need thermal paste because of the peaks and troughs on the heatsink AND the processor. Keep in mind the lid of your processor is not a mirror finish :smoker:

Thermal paste is needed. You might be able to get away with it w/o the thermal paste but your temps will be a fair bit higher.

 

[ShepsCrook]

Ok, one thing that people avoided is the initial statement. We all know that unless you buy a used Heatsink, it comes "pre-lapped." But what if you eventually down the road want to maybe put in a higher grade thermal paste or you buy a used heatsink, or whatever the case may be. You need to perform what's called "Lapping" or "Re-lapping" of the heatsink.

This is usually done with 1500 grit sand paper, then clean it off, then 2000 grit sand paper, then clean it off. And lastly, 3M's rubbing compound with a microfiber or something of the sorts. Then clean it off again. Make sure to use 99% isopropyl alcohol which you can pick up at CVS or Walmart or wherever. As far as the sandpaper goes, Wal-mart, Autozone, or a car parts store should have them, along with the 3M Rubbing compound.

I've performed these steps many of times and keep a good stock of the items required for this around here.

 

[LeeJend]

Unless you get a heatsink with visible ridges or machining marks in it don't bother lapping. You are more likely to do harm than good. As well as having a mirror finish the heatsink needs to be flat. Hand lapping usually ends up with a convex surface because you don't apply pressure evenly to the entire area being worked.

Thinking about it, if you have machining marks on the heatsink get rid of it, it's junk. (Yes, I had one like this.)

Polishing the top to remove oxide from an old HS is worth it. Just use a cotton clothe or a buffing wheel in a dremel tool. No sand paper or scotchbrite.

PS Don't even think about lapping a cpu top. It will remove the part number making it worthless and the chance of getting metal debris between the 940 odd pins is not worth the risk.

 

[ShepsCrook]

I wouldn't say it's junk. If done properly, like a sanding block or whatnot, your heatsink will be in excellent quality.

 

[Steevo]

I have lapped my ATI cooler and gained, as well as my Arctice Cooler64.


But I have a very nice honing stone and oil that I use, then to polishing compound to get that mirror shine.


All I gained was 2C on my ATI though, so generally it isn't worth it.

 

[Sazar]

My cpu temps dropped about 5-6 C (depending on the fan speed) and I can keep it running slower. It is quieter even at the highest settings than my old cpu hsf

For my video card, the old ati one sounded like one of the bearings was a little poopy and it was a little loud, so I just bought a new one.

 

[ShepsCrook]

I usually lap after I've let a heatsink sit for a few years. I generally get a gain after lapping. But your drop in temperature is rarely large, but if you're talking about that breaking 2c that causes your machine to fail or not, it's worth it. It's easy to do and very satisfying when you can make it into a mirror.

 

[ElementalDragon]

i was quite impressed by the lapping job on the bottom of my two Zalman VF900's that i got to help keep my video cards nice and cool. makes me wish i ordered that Zalman CNPS9500LED way back when, instead of the Arctic Cooling Freezer 64 Pro. then again.... if i had done that.... then i'd probably have 3 fan speed controllers hanging out the back of my case. lol.

 

[ShepsCrook]

I have a fan controller in the front, but I would really love it if someone made a wireless fan controller or something. Instead of having one on the front or back of the case...

 

[ElementalDragon]

that'd be....... annoying? what'd happen if the battery in the wireless controller died? you'd wind up having full fan speed, or none.

 

[ShepsCrook]

So you make it run off of 3 or 4 AA's. And it alerts you when it's running low. As well as an activity time out. I mean, how often will you use it that you would drain the batteries THAT fast?