Heatspreader lapping

Hi Logan and Wendel,

So, there have been a lot of videos about heatsinks recently. Sure, you can drop up to $200 on a fancy cooling solution but why when you can get an extra 10-15˚C out of your current heatsink?

The weakest point on most off the shelf cooling solutions is the Thermal Interface. Creating flat surfaces is something that most manufacturers fail at badly.

Heatsink spreaders are often ground with large radius grinding wheels, not orbital or planar ginders. This means that despite the shiny surface, the curve of the surface minimises the contact area. CPU spreaders are not much better. They appear to be very flat but once you start grinding them you will find you have to remove a lot of material to get a flat surface.

If you take the time to lap both sides of the interface and then correctly apply thermal grease, you will most likely see a dramatic improvement in performance. I have lapped 3 thermal interface pairs in the past, in every case I saw an improvement. The improvements I saw were 13, 15 and 18 ˚C under load with similar improvements at idle.

Another effect of the lower thermal resistance is that your fans will kick in less often. Lower resistance means that you need a smaller temperature difference for an equivalent heat flow. Since the heatsink does not need to be so cold to cool the chip, the fan is less likely to kick in at a given temperature.

It's a Win Win Win Scenario. Cooler chips, Less fan activity, Awesome story of that one time you sanded you CPU.

It would be great to do a before and after video with some heatsink and spreader lapping.



Probably worth mentioning that the 'proper' way to apply thermal grease is to use a tiny amount and spreak it out thinly over your cpu. I cringe whenever I see people squirting big coils of expensive compound all over their chips.

Thermal grease is a shitty conductor of heat, it's just there to replace air, which is a shittier conductor.

The method I ususally use is to push my finger through a cheap plastic bag. If you're careful this will result in a thin layer of plastic tightly covering your fingertip. Using the wrapped finger, you spread a very small amount of the grease onto the chip. The amount should barely be enough to cover the metal heat spreader.

Of course, if you haven't lapped your heatsinks then you'll still have a shitty thermal interface, just a slighty less shitty one.

Whoever invented Thermal Pads should be shot. A 0.5-2 mm layer of thermal grease will kill your performance.

I was with you until you said you used the manual application method, with your finger, wrapped in a bag. Not only does that introduce impurities, but it completely defeats the purpose of putting a small amount of TIM in the center. Use a little less than a grain of rice, directly in the middle, and let your heatsink, or waterblock, do the spreading.

this is all i could think of haha


Applying and spreading the Thermal paste yourself does nothing but use too much, and cause air bubbles. As well as allowing dust and contaminants to enter.

Lapping was used some years ago on the Core 2 Duos and quads and was very effective. I see no reason as to why it would not be effective today as well.

De liding of the Ivy bridge and Haswell has also proved effective (if not a bit risky) due to the poorer quality thermal interphase used in these chips. The Sandy Bridge chips were soldered to the heat spreader.

Spreading of TIM with fingers is a no no, as some of the other fine people on this forum have already stated. The "Rice grain" method is highly recommended.