Thermal compound, also called thermal grease or thermal transfer paste, is a substance used to help fill in the tiny gaps between the surface of a processor and a heat sink to promote better heat exchange. There are different grades of thermal paste, each with its own unique chemical makeup. These can be made of a combination of bonding materials like various types of silicones, urethanes or epoxies and the material that has high thermal conductivity (like silver, aluminum or even diamonds ground to a very fine powder and mixed into the glue).
Most mainstream CPU thermal pastes are sold as liquids. They may be kept in a syringe-style bottle or jar and are applied by putting a small dab of the product on the center of the processor. Then the heat sink’s connecting part is lowered onto the processor and pressed down to spread the thermal grease evenly across the surface of the chip. It is very important to use a good amount of compound, but not so much that you end up smearing it all over your motherboard and other components, which will prevent them from cooling properly.
We tested a number of liquid metal and ceramic-based thermal compounds to see how they compare with one another. The results show that the ceramic-based products come very close to their metal-based counterparts in most cases, with just a few degrees of difference. As for the metal-based products, they’re still a few degrees hotter than the non-metal ones.