Definition
Thermal resistance quantifies how strongly a material, joint, or path opposes the flow of heat, much as electrical resistance opposes current. It is expressed in degrees Celsius per watt (°C/W): the number tells you how many degrees a junction will rise above its surroundings for each watt of heat it must shed. Lower thermal resistance means heat escapes more easily and chips run cooler at the same power.
The cooling chain
The total resistance from a chip's silicon junction to the ambient air is a sum of stages, often written as junction-to-case, case-to-sink, and sink-to-ambient. Each link in the chain, the chip package, the thermal interface material, the heatsink, and the airflow over it, adds its own resistance. The interface material's contribution depends on its thermal conductivity, its contact area, and its bond-line thickness; a thinner, more conductive layer over more area lowers resistance, which is exactly why a well-applied thin paste layer beats a thick one.
Why miners should care
For a fixed heat load, every °C/W in the path translates directly into hotter chips, and hotter chips throttle, age faster, and waste energy. Understanding the chain explains why fixes target the weakest link: fresh paste cuts case-to-sink resistance, a cleaner or larger heatsink cuts sink-to-ambient, and better airflow or liquid cooling attacks the final stage. Diagnosing a hot miner is, in effect, finding which resistance in the chain has crept up.
For the interfaces and parts that make up that chain, see Thermal Paste and Heatsink.
In Simple Terms
Thermal resistance quantifies how strongly a material, joint, or path opposes the flow of heat, much as electrical resistance opposes current. It is expressed in…