How to Lap a CPU Processor

In an overclocked computer, thermal efficiency is everything. All modern processors have an aluminum- or nickel-plated cap, called an integrated heat spreader (IHS). This gives the processor heat sink a solid surface to be mated with. However, every IHS has microscopic gaps that reduce the surface area that comes into contact with the heat sink. By lapping your processor, you smooth away these gaps and expose the copper surface beneath the plating. This can lead to a temperature reduction of as much as 10 percent, resulting in more stable operation and the ability to reach higher clock speeds.

Things You'll Need

• Cotton swabs
• Acetone (nail polish remover)
• Sandpaper (220, 400, 600, 800, 1000, and 1500 grit)
• Flat work surface

Instructions

1. Clean all residue from the surface of your processor using cotton swabs and acetone.

2. Place 220-grit sandpaper on your work surface. Glide your processor over the sandpaper using a slow, circular motion. Use even pressure on the processor and let the sandpaper do the work.

3. Check your work every 5 minutes by examining the surface of the processor. You will probably find that the plating is not wearing off evenly; this is a sign that the processor would not have made even contact with the heat sink. Your goal is to expose all of the copper beneath the IHS; this will take approximately 10 to 15 minutes of sanding.

4. Stop sanding when the nickel or aluminum plating has been removed and the copper surface has been exposed. Discard the 220-grit sandpaper and place the 400-grit sandpaper on your work surface. Continue sanding.

5. Use increasing grits of sandpaper as you continue lapping. Each grit will require less sanding time than the one before it. In all, the lapping process will require approximately 30 minutes of sanding.

6. Stop sanding when the surface of your processor is smooth and shiny. Resist the temptation to sand your processor to a mirror finish; there is little benefit in doing this.

7. Clean the microscopic metal shavings from the surface of your processor using the cotton swabs and acetone. Allow several hours for the processor to dry completely before installing it in the computer.

Tips & Warnings

• Use a high-quality thermal compound such as Arctic Silver when installing your lapped processor. A very small amount of compound--approximately equivalent to a grain of rice--is all that is required. Spread this evenly over the surface of the processor, then install the heat sink.

• Avoid being overzealous when lapping your processor. Lapping reduces the height of a processor, and if taken too far will reduce the height so much that the heat sink can no longer make firm contact. The goal of lapping is to expose the copper surface beneath the processor's aluminum heat spreader for enhanced heat transfer, then smooth away as many of the microscopic imperfections as possible. Once this has been accomplished, stop sanding.

• Never attempt to lap a processor that you cannot afford to lose, or that you will not be overclocking. Lapping a processor is completely unnecessary for keeping it cool at its stock speed, voids the processor's warranty and may permanently damage it.

References

• Frosty Tech: Guide to Lapping Your CPU
• NeoSeeker: CPU and Chipset Lapping Guide
• OC3D: Guide to Lapping an Intel LGA 775 Processor