How To Apply A Coating Of Thermal Paste To The CPU And Heatsink To Maximize System Cooling

Posted on: 15 July 2016

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You know how important data center hardware maintenance is. Keeping your systems cool is essential to providing long-lasting, reliable service for your internal and external clients, and maintaining as close to perfect as possible contact between central processing units (CPUs) and their heat sinks is the starting point. If heat isn't allowed to efficiently dissipate from the CPU, then you can expect problems to develop due to thermal stress. Worse, damage could occur if the heat buildup is left unchecked, resulting in costly down-times and equipment repair or replacement. One of the most important means of maintaining efficient heat flow from CPU to heat sink is to use thermal paste as a transfer medium. Below is how you can remove old paste, when necessary, and replace it with a new application:

How thermal paste works

The metal surfaces of the CPU and heat sink appear smooth to the naked eye, but they actually contain microscopic irregularities that form tiny air pockets when the surfaces are mated. These air pockets are excellent heat insulators, and prevent heat transfer across the joint between the CPU and heat sink. However, this problem can largely be solved by filling the air gaps with a thermal conductor; the most effective means of doing so is by using thermal paste. Thermal paste consists of a thick fluid binder that carries heat conducting materials; these materials include diamond, silver and a variety of other elements and compounds that are excellent conductors.

Thermal pastes generally possess a long lifespan, but they can break down over time, particularly if exposed to excessive heat. That is why thermal paste will need replacing on occasion, and you can perform this task yourself provided you are comfortable working inside the case of your system components.

Step-by-step instructions for applying thermal paste

1. Remove old thermal paste from the CPU and heat sink - Once you have opened the case and removed the heat sink from the CPU, you will immediately notice the presence of thermal paste on the surfaces where the two components are joined. This paste may still be in a liquid state or it may be dried and flaking. No matter its condition, it will need to be removed.

To clean the thermal paste, begin by dampening a paper coffee filter or other lint-free paper or cloth wipe with isopropyl rubbing alcohol. Be sure to use as high a percentage of rubbing alcohol as you can find, and avoid formulations that contain any other additives or large amounts of water. Next, carefully rub the CPU and heat sink in a circular motion to remove the thermal paste. Do not allow alcohol to run down the side of the CPU onto the circuit board and replace the wipe with a fresh one once the previous one is soiled. After removing all the thermal paste, allow the components to air dry for a few minutes.

2. Apply new thermal paste to the CPU - When the old paste has been removed, the next step is to apply a new coating to the CPU surface. Though there are several possible ways to do so, a simple and effective means is to place a single pea-sized drop in the middle of the CPU. When squeezing the paste from the tube, avoid making air bubbles by working slowly and keep the paste as centered as possible. If you accidentally apply too much, then wipe away all of the paste and apply a fresh coating.

3. Mate the heat sink to the CPU - After applying a small amount of thermal paste to the CPU, the last step is to reattach the heat sink to the CPU. Carefully center the heat sink over the CPU, while aligning the mounting holes over their respective hold-down bolts, then lower the heat sink slowly onto the top of the CPU. Be sure to keep the heat sink as level as possible so its entire surface meets the CPU simultaneously. After lowering the heat sink all the way, place the nuts on the hold-down bolts and tighten them by hand. Carefully examine the edges of the joint between the CPU and heat sink and look for signs of thermal paste protrusion; should you see any, you will need to remove the heat sink, clean the thermal paste and repeat the application.