Thermal Paste: The Vehicle of Cool

May 8, 2009 Hardware — Andrew Goldberg

Ever wonder why that green stuff in your car’s radiator is so important? Those of us that have a car with a leaky cooling system know that sitting in traffic puts the temperature needle in the red zone —  which has the potential to destroy the engine. The green coolant transfers heat from the engine to the radiator, keeping the engine cool and happy.

Thermal paste applied to the surface of a processor serves a similar purpose. During normal operation, a computer’s processor generates heat that transfers via thermal paste to a heat sink. The heat sink can be cooled either by a fan or a liquid cooling system. If you reassemble a computer without using thermal paste, air is the only substance to conduct heat between the processor and the heat sink.

A pocket of air surrounding your body insulates your skin from a cold environment. This effect is exactly what we do not want to subject our processor to. An insulated processor will quickly overheat, most likely causing permanent damage. Thermal paste is an excellent conductor of heat and is essential for keeping the processor temperature in check.

We created a guide on how to remove and apply thermal paste correctly. This procedure was performed on a MacBook Unibody, but the general steps can be used for any computer, whether Apple, PC, desktop, or laptop. However, be mindful that you never have to re-apply thermal paste during regular computer maintenance — only when you separate a processor from a heatsink. We love keeping you and your computer happy, and we hope you find the guide useful!


  1. One doesn’t need to apply that much thermal paste as was shown. Wrap some plastic (like you would get from a plastic sandwich bag) around your finger and apply a drop of Arctic Silver paste to that. Then just take your finger and applying pressure, rub that small amount evenly onto all areas of the processor heat transfer pad. A very thin layer will be enough to transfer the heat to the heat sink. In theory, you only need enough paste to fill the nearly microscopic gaps between the two mating surfaces. If you put a glob of paste on the processor, most of it will just squeeze out when the heat sink is pressed down and be wasted.

    Comment by Constable Odo — May 8, 2009 @ 7:43 pm

  2. You’re right, we were a little overzealous in the first photos we posted. We’ve since updated the photos to show using less thermal paste. You just want to apply a very thin coat evenly to the surface of the chip.

    Comment by kyle — June 5, 2009 @ 6:55 pm

  3. I did not see how often this should be undertaken. For example, older Macs.

    Comment by GS — June 5, 2009 @ 7:03 pm

  4. It should be mentioned early in this thread that this is really NOT a routine or 60,000 mile scheduled maintenance like flushing the anti-freeze or transmission fluid. If you must yank the CPU for some good reason use thermal paste when you replace it.

    Keeping the fins on your heat-sink reasonably free of dust is maintenance.

    Comment by Bryan Crawford — June 6, 2009 @ 11:03 am

  5. This is why we love comments. I added a couple of lines near the end of the article to explain that thermal paste application is not a “preventive maintenance” procedure. It should be undertaken only if for some reason you need to separate a processor from a logic board.

    Comment by miro — June 17, 2009 @ 2:02 pm


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