hermal paste is used to fill microscopic gaps and imperfections between the metal surfaces of the processor and the heatsink. These imperfections can trap air, which has poor thermal conductivity, hindering heat transfer. The thermal paste fills these gaps to ensure better contact and thus better heat dissipation.

Good thermal paste can significantly reduce the operating temperature of a processor, thereby improving performance and prolonging the lifespan of the component. It helps prevent thermal throttling, where the processor reduces its speed to prevent overheating.