Thermal Paste
What it does
A desktop processor will generate a lot of heat when used. If the processor gets too hot, it may be damaged. To prevent this, a CPU-cooler will be used and the bottom of the cooler and the top of the CPU will both be flat so that the two can touch each other over the largest possible area. This maximizes the heat transfer between the CPU and the cooler. Because there will be small imperfections in these two touching surfaces, there will be small gaps where heat will have to flow through air to get through and the air is a terrible conductor. Thermal paste is a thermally conductive material that, although normally not as conductive as metal, is much better than air. Thus a thin layer of thermal paste will push out the air, connecting the CPU with the cooler and allowing heat to flow from the CPU into the cooler.
What to look for when buying
There are four important properties to consider when buying thermal paste.
- Thermal Conductivity
- Electrical Conductivity
- Aging
- Price
Applying Thermal Paste
Preparation
If the CPU or cooler has a plastic protection film peel off that film. If it is left on, it will impede heat flow making the computer overheat.
If the CPU and/or cooler are not new, clean off the CPU and cooler as best as possible. This can be done with paper towels and 70% isopropyl alcohol to remove the bulk of the old paste. Then, a microfiber cloth should be used to remove any stray fibers from the paper towels.
Application
For a normal (non-liquid metal) thermal paste, apply a small pea-sized dot of paste to the center of the CPU and then mount the cooler. Screw on the cooler slowly, going a few twists at a time, making an X pattern with the goal to have the cooler spread out the paste evenly through pressure.
Burn in
It can take some time for the thermal paste to settle in, some pastes may work slightly better after a few days worth of using the computer.
Trouble Shooting
- Unable to easily separate CPU from cooler
- Explanation: The paste may have dried and hardened "gluing" the CPU to the cooler
- Fix: Heat the paste to weaken it by turning on the computer
- Note that it will take time to heat the paste so if the computer is overheating, you might want to just idle for a while instead of hitting max temp and shutting down immediately.
- This may weaken the paste sufficiently to pry the CPU apart from the paste.
- Warning: when removing the CPU from the cooler, try to avoid scratching the connecting surface, scratches here may impede heat transfer.
Recommendations
At the moment the time of writing Arctic MX-4 is suggested for standard use. It is affordable, easy to apply and has a good track record. If a 2-degree difference is important and a slightly harder application is acceptable, Thermal Grizzly Kryonaut can perform better but it is multiple times more expensive then Arctic MX-4 and has a thicker, harder to apply the paste.
Last updated by rotclanny on Jul 9, 2023