Heatsink Lapping

antivenom · Post by **antivenom** » Wed Feb 18, 2009 2:52 am

If anyone doesn't know, heatsink lapping is the process of polishing the bottom of a heatsink to a mirror shine in order to removed any microscopic grooves which can create air pockets which prevent thermal compounds from creating a perfect contact between the heatsink and the CPU heat spreader.

Now apparently, after researching this a bit, lapping can lower CPU temps by ~4Â°C which in my opinion is pretty handy. But the guides I've read seem to be a little old, and I was wondering whether lapping, in this day and age, is worth the time and effort?

I ask because I have a Xigmatek S1283 which has a very rough bottom and I've been thinking about lapping it, but would this be possible with a HDT (Heatpipe Direct Touch) heatsink?

burebista · Post by **burebista** » Wed Feb 18, 2009 3:02 am

Of course you can, but take care not to end like this.

You can take a look here to see a TIM application method for HDT coolers.

blackworx · Post by **blackworx** » Wed Feb 18, 2009 3:03 am

From personal experience I got good results with lapping, but I don't know about HDT coolers. I was under the impression that lapping was more about flattening uneven contact surfaces than smoothing out microscopic grooves (although the extremes some people take it to and the whole "mirror shine" thing seems to suggest many people believe otherwise). My gut feeling is that microscopic grooves would actually aid cooling by increasing the contact surface area. I have no idea about HDT coolers, but I doubt it could hurt. You'd have to be wary of the pipe wall thickness as you'd have much less leeway with bare pipes than you would with a solid block of metal, especially considering they have already been ground down at the factory.

antivenom · Post by **antivenom** » Wed Feb 18, 2009 4:10 am

Hmmm... does anyone have any idea how thick the bottom of the pipes are on HDT coolers? Because I'd hate for mine to end up like that picture.

Does anybody have any other little tips for dropping CPU temps?

blackworx · Post by **blackworx** » Wed Feb 18, 2009 4:47 am

antivenom wrote:Hmmm... does anyone have any idea how thick the bottom of the pipes are on HDT coolers? Because I'd hate for mine to end up like that picture.

By the looks of that pic - not very

.

Does anybody have any other little tips for dropping CPU temps?

Switch off your PC (sorry couldn't resist).

On a more constructive note, your HDT cooler will be pretty flat since they are ground down at the factory (almost certainly on a flat sanding disc) so you might get some benefit from lapping your CPU heatspreader to make it equally flat. Might get a few degrees benefit out of that - plus lapping the CPU is much easier than lapping the heatsink.

Post by **NeilBlanchard** » Wed Feb 18, 2009 3:23 pm

Hi,

The direct touching heatpipes are supposed to deform a little, if the CPU heatspreader is not flat. The copper pipes are rather soft, and by deforming them, they make better contact.

Save your effort -- the HDT-S1283 will not benefit from lapping. In fact, it may hurt it.

What temperatures are you getting? Have you tried undervolting the CPU?

xan_user · Post by **xan_user** » Wed Feb 18, 2009 3:42 pm

lapping a tower is nearly impossible. the mass at the top tends to make the HS wobble as you lap it, so its really - really difficult to end up with a flat surface.

thejamppa · Post by **thejamppa** » Wed Feb 18, 2009 3:45 pm

usually heatsink is not need of lapping, its heatspread on CPU that usually is more distorted...

antivenom · Post by **antivenom** » Fri Feb 20, 2009 2:54 am

Well currently, the temps of the 4 cores range between 28 and 37Â°C which to me seems to be a rather large gap which made me think lapping may benefit me. I have my S1283 fitted to my motherboard with a Thermalright bolt thru kit, are these susceptible to bending the motherboard and impairing the contact between heatsink and heatspreader?

Kate · Post by **Kate** » Sat Feb 21, 2009 1:17 am

Hi there!!

LOL 28C!! I would be laughing if i could have that kind of temperature... If you can read my post:

viewtopic.php?t=52398

Post by **NeilBlanchard** » Sat Feb 21, 2009 6:41 pm

Hi,

I think the difference in the core temps are due to: different loads on those cores, and/or different calibration/accuracy of the temperature sensors.

Relax -- both of you! Your temps are FINE!

thejamppa · Post by **thejamppa** » Sun Feb 22, 2009 5:12 am

I agree with Neil... They're not that bad temps... Enjoy computers...

antivenom · Post by **antivenom** » Sun Feb 22, 2009 7:16 am

True, I suppose I've got nothing to worry about, I was just thinking 9-10c difference was a lot but varying loads would explain that.

Thanks guys.