Introduction

Before we begin we’ll discuss what it means to lap a aluminum or copper heatsink and why you may want to do it in the first place. The surface of a factory heatsink may not be very smooth. Any imperfections on the contact surface of the heatsink will reduce its ability to transfer heat. When you lap a heatsink you’re actually sanding down the surface of the metal. This effectively removes any build-up and makes the surface more flat.  Inevitably, the surfaces of the heatsink and the CPU heatspreader will not contact perfectly. This is where thermal compound comes into play. Thermal compound is a liquid substance that improves surface-to-surface conductivity by filling in the tiny gaps between the heatsink and the heatspreader. Arctic Silver 5 is the compound-of-choice for all Electrical Ninjas.

Results of lapping a heatsink can vary dramatically. Most stock heatsinks will cool the processor by an additional 1-2 degrees (C) under full load after a successful resurfacing. Damaged heatsinks or those previously used with inferior thermal compound may experience up to 5 degrees (C) decrease in full-load temperatures.

Materials required:

• Aluminum or Copper Heatsink (ZALMAN,  COOLER MASTER, ARCTIC COOLING….)
• Sandpaper (3M Wet/Dry Sandpaper)

  • 400 Grit Wet/Dry

  • 600 Grit Wet/Dry

  • 800 Grit Wet/Dry

  • 2000 Grit Wet/Dry

• Flat surface
• Water
• Dishwashing Liquid Soap
• Tape

Aluminum or Copper Heatsink:

Both Aluminum or Copper Heatsin’s can be found all over the web including Newegg.com and TigerDirect.com. There are several brands to choose from ZALMAN, COOLER MASTER, ARCTIC COOLING and even more. We will keep you posted on our opinions about these heatsinks. Many CPU’s come with a stock heatsink.

Sandpaper:

I used 3M Wet/Dry Sandpaper. It can be found at Wal-Mart or AutoZone. I paid $4.29 plus tax for the assortment pack that included 400 – 800 grit and another $4.29 plus tax for the 2000 grit at AutoZone. For a better finish you can also include steps using 1000 grit and 1500 grit sandpaper.

Flat surface:

For a flat surface I used a glass pane (8” x 10”). Although most people don’t have sheets of glass lying around, Home Depot will part with a pane for $1.85 plus tax. If you don’t feel like using glass you can use any flat, hard surface. It is important to only use a surface is that extremely flat because any imperfections in the surface under the sand paper can (and will) cause your final conducting surface to have grooves.

Water:

If you don’t have water, I can’t help you. I did all my work in a bathroom… it’s where we ninjas hide our water.

Liquid Dishwashing Soap:

You can use almost any liquid  dishwashing soap. I used DAWN antibacterial which left me with a resurfaced heatsink and a pair of clean-smelling hands. The dishwashing soap acts as a lubricant during the sanding process.

Tape:

I used electrical tape. It worked.

Lapping the surface

Begin by soaking the 400 grit sand paper in water for 10 seconds. Once it’s wet, place the sand paper on a flat surface and tape it down. Put a bead of soap on the bottom of the heatsink and rub it around until the entire conducting surface is coated lightly.

Now place the heatsink (heat-conducting side down) on the sandpaper, push down lightly and hold the heatsink flat while moving it back and forth 20 to 30 times. If the resistance increases noticably, stop and apply more dishwashing soap to the heatsink. After you’ve made 20-30 passes, rotate the heatsink (90 degrees) and make another 20 – 30 passes. You should continue this process until you’ve sanded the heatsink from all four different orientations. Now clean the heatsink’s surface and admire your handywork. If you are not satisfied, you can repeat this using the same sandpaper. Once you are satisfied conduct the above steps for the 600, 800 , 1000, 1500, and 2000 grit. When you are finished, clean the heatsink’s conducting surface with water, let it dry, then clean it again with rubbing alcohol and a lint-free cloth or Q-tip. If anything goes wrong during this project, you can always start from the beginning.