Whether you’re building your very first computer or trying to fix a laptop that won’t start, thermal paste is an essential part of the process. It’s what transfers heat from the processor to the fan and then out into the air, preventing overheating and sudden shutdowns. But not all thermal paste is created equal, and some require reapplication on a regular basis to keep your PC running efficiently.

The best way to evaluate a brand of thermal paste is to compare its performance to other brands by conducting tests. The most common method involves measuring the idle temperature of a computer, applying the given brand of thermal paste to the CPU, and then running the CPU through a stress test. The lower the difference between the idle and the stress test temperatures, the more efficient the paste is.

Other important features to consider include electrical insulation, density, and compatibility with your motherboard and processor. Zinc oxide-based compounds are popular and usually work well for most systems. Silver-based formulations offer better thermal conductivity but can be electrically conductive and cause malfunctions if they leak onto other components. Some pastes also contain diamond powder which offers excellent thermal conductivity, but is comparatively more expensive.

To apply a thermal interface compound, first make sure the surface is clean and free of dust or other impediments to heat transfer. Then, using a finger or a small spatula, put on a thin layer of the paste. It’s important to spread it evenly over the surface, otherwise hot spots could develop that lead to a CPU failure.