Thermal Grease
Thermal Grease

Thermal compound, also known as thermal paste, thermal grease, heat paste, or CPU paste, is a thermally conductive chemical substance used as an interface between heat sinks and heat sources such as a computer’s central processing unit (CPU). The primary purpose of thermal compound is to eliminate air gaps or spaces from the interface area in order to maximize heat transfer and dissipation.

The Importance of Thermal Compound Heat is a natural byproduct of electronic devices at work, particularly in CPUs and GPUs (Graphics Processing Units). If this heat is not properly dissipated, it can lead to overheating, which can reduce efficiency, cause hardware to throttle, or even result in permanent damage. Thermal compound plays a critical role in preventing these issues by enhancing the thermal conductivity between the components.

How Thermal Compound Works

The surfaces of a CPU and a heat sink are not perfectly smooth; if you were to look at them under a microscope, you’d see a landscape of peaks and valleys. When the two surfaces mate, these imperfections create tiny air pockets that trap heat because air is a poor conductor of heat. Thermal compound fills these microscopic gaps and allows for better heat transfer.

Types of Thermal Compounds

There are several types of thermal compounds available, including:

  • Silicone-based pastes, which are generally more affordable and easier to apply but offer lower thermal conductivity.
  • Metal-based pastes, which contain fine metal particles, typically silver or aluminum, that provide excellent thermal conductivity but can be electrically conductive and more challenging to apply.
  • Ceramic-based pastes, which are not electrically conductive and offer good thermal conductivity without the risk of short-circuiting electronic components.
  • Carbon-based pastes, which include graphite or diamond powder and offer high thermal conductivity and stability.


Applying thermal compound is a delicate process that involves placing a small amount of the paste onto the CPU before installing the heat sink. The goal is to apply enough to cover the surface without it spilling over the sides. There are various methods for application, including the pea, line, and spread methods, each with its advocates.

Maintenance and Replacement Over time, thermal compound can dry out and lose its effectiveness. It’s generally recommended to replace the thermal compound every few years or when components are being upgraded or replaced.


Thermal compound is a small but essential component in the construction and maintenance of a computer so you should always have some laying around in case you need it. It ensures that heat generated by the CPU is efficiently transferred to the heat sink, keeping the system cool and stable. Whether you’re building a new PC or maintaining an existing one, understanding and correctly applying thermal compound is key to the longevity and performance of your system.


  1. How often should I replace the thermal compound on my CPU? It’s recommended to replace the thermal compound every 2-3 years or when you notice temperatures are higher than usual, indicating the compound may be drying out or degrading.
  2. Can I use too much thermal compound? Yes, using too much thermal compound can actually insulate the CPU and prevent proper heat transfer. It’s important to use just enough to cover the surface without excess spilling over.
  3. Is thermal compound necessary if my CPU and heat sink are flat? Even if the surfaces appear flat, there are always microscopic imperfections. Thermal compound is necessary to fill these gaps and ensure efficient heat transfer.
  4. What’s the difference between thermal compound and thermal pads? Thermal pads are pre-cut pieces of thermally conductive material that can be used instead of thermal paste. They are easier to apply but generally offer slightly lower thermal conductivity.
  5. Can thermal compound affect the performance of my computer? While thermal compound itself doesn’t boost performance, it enables the CPU to operate at optimal temperatures, which ensures that it can run at full speed without thermal throttling.
Eric Chan

Hi! I’m Eric and I work on the knowledge base at  You can see some of my writings about technology, cellphone repair, and computer repair here.

When I’m not writing about tech I’m playing with my dog or hanging out with my girlfriend.

Shoot me a message at if you want to see a topic discussed or have a correction on something I’ve written.

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