Lapping the processor heatsink is the process of creating a super flat, smooth surface that will enhance heat exchange and increase the heatsink's overall efficiency.

You can also find a guide with pictures here. Skip down about half way to "Tools to be used".

This is accomplished by sanding the mating surface of the heatsink (and/or the processor core itself) until it has a perfectly flat, smooth surface. Most heatsinks are not perfectly flat which will cause small air gaps between the processor core and the heatsink. This reduces the heatsink's ability to transfer heat away from the processor core.

Use waterproof sandpaper (sometimes called wet or dry) Use lots of water, the water flushes the metal particles away, keeps the sandpaper clog free.

All that is required is a flat surface (glass table works nicely), 400 and 600 grit sand paper to start, and some elbow grease. Lay the 400 grit sandpaper, grit side up, onto your work surface (glass table).

Using only the weight of the heatsink, begin sanding the mating surface of the 'sink in a "figure eight" motion. Rotate the heatsink every so often to avoid sanding in the same direction too much. Do this until a uniform reflective surface is achieved. Repeat Using finer grit sandpaper will help improve heat transfer: 1500 is certainly fine enough, but since you need to get such fine grades at an automobile parts store (it is used for finishing automobile paintwork), you might as well get a sheet each of 600, 800, 1000, 1500, and 2000, an aluminum heatsink should have almost a mirror finish.

Each time you change to a finer grit, carefully wash the work surface, your hands, the heatsink, and the sandpaper. Any larger grit left when you start with a finer grade will leave visible scratches.

After the heatsink is lapped and cleaned, install in the usual way with thermal compound (Arctic Silver). Depending how flat the surface of the heatsink was to begin with, there should now be a reduction in CPU temperature.

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by FastEddie
last modified: 2004-02-07 13:53:53