How To Apply Thermal Compound

Author: Curt Riedy

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Intro | How It Works
A Bit of Warning
The Steps | Things to Remember

If you’re a hardcore overclocker, there’s little debate to just how important keeping your CPU cool is. The extra stress that comes with overclocking your PC can place an enormous amount of pressure on your CPU cooling system. However, thanks to the majesty of thermal compounds, your heavily modded system has a great deal of hope.

By using a thermal compound (especially one of a higher quality), your heatsink will be able to effectively evacuate heat from the core. By taking this extra effort, your PC will be able to experience lower temperatures at both idle and load.

So How Does It Work?

Thermal Compounds are primarily used to assist a heatsink in drawing heat away from an integrated circuit or transistor. The paste increases the efficiency of your PC by filling in the air gaps within the heatsink, which often occur when the irregular surface of a heat generating component presses itself against the heatsink surface. When using the compound on a CPU, the grease is often applied on both surfaces with a small plastic spatula or similar device.

A Bit of Warning:

The thermal conductivity of the compound is actually much poorer than the metals they couple. When applying the compound, it would be in your best interest to use no more than necessary when trying to exclude air gaps. The paste must be thin enough that it doesn't inhibit thermal contact between the heatsink and CPU, but thick enough to ensure that the heatsink and CPU are in adequate contact with one another. A large amount of excess grease separating the metal surfaces will only further degrade conductivity.

The Steps:
  • Open your computer case. Clean both the bottom of the heatsink and the raised die of the CPU. A preferred way to remove any silicone oil-based thermal grease from a component or heatsink is by using isopropyl alcohol, a rubbing alcohol. Wipe these surfaces down with a damp, alcohol-soaked tissue or light cloth. Both surfaces should be dust-free (a can of compressed air is recommended for this process). Let both surfaces dry.

  • Using the syringe, squeeze a tiny drop of grease (somewhere between 1~2mm in size should be ideal). On occasion, the clamping pressure can be very high, so squeeze the heatsink on to the chip and most of the excess grease should be forced out.

  • Using the appropriate twist or angle, carefully pull the heatsink vertically off of the chip. Take a moment to examine the amount of grease contained on the heatsink and CPU. If you look closely, you should be able to see little raised peaks (or ridges) spread evenly over both the chip and heatsink. These are the areas where there is good contact between both components.

  • Reinstall the heatsink and remove it again to check. If both CPU die and heatsink are reasonably flat, you should be able to see through the thermal grease and see the color below the little peaks of grease. Note the ridges of grease on the CPU die in some of these pictures-- those are areas of excess grease. Any areas of poor contact should be filled in with a tiny dab of grease.

  • Take another moment to examine the heatsink. You should be able to see the excess grease around the edges of the area where the grease is located. Don’t worry, this is actually quite normal. While you can try to wipe some of it off, you absolutely do not want to touch the center area with any of the grease. It’s incredibly important that the contact on both the CPU die and heatsink should be both even and continuous.

  • If everything is up to par, install the heatsink, plug in your CPU fan and take in that deep sense of pride that comes along with a job well done.

Once again, two of the most important factors to applying the thermal paste is 1) being able to see the color of the surface through the thermal grease and 2) having an even distribution of the tiny peaks all over the CPU and heatsink contact areas. Remember these, and you should be well on your way too experiencing the lower temperatures you and your PC so rightfully deserve.