Thermal resistance, the English name is thermal resistance, that is, the hindering effect of objects on heat conduction.

The concept of thermal resistance is very similar to that of resistance, and the unit is also similar - °C/W, that is, the temperature difference between the two ends of the heat conduction path when the continuous heat transfer power of the object is 1W. In the case of a heat sink, the two ends of the heat conduction path are the heating object (such as the CPU, etc.) and the ambient air.

Heat sink thermal resistance = (heating object temperature - ambient temperature) ÷ thermal conductivity.

Obviously, the lower the thermal resistance of the heat sink, the better - under the same ambient temperature and thermal power, the lower the thermal resistance, the lower the temperature of the heating object!

It must be noted that the above formula is "thermal power", not "heating power"! Because it is impossible to guarantee that all the heat generated by the heating object is conducted and dissipated through one path of the radiator, any low-temperature object (including air) in contact with the heating object may become its heat dissipation path, and even heat can be dissipated by thermal radiation. Therefore, when the temperature of the environment or the heating object changes, even if the heating power remains unchanged, the heat conduction power of the radiator may change greatly due to the change of the heat dissipated through other channels. If it is calculated by heating power, there will be a phenomenon that the thermal resistance of the radiator is different at different ambient temperatures.

To sum up, the thermal resistance value marked on the radiator (not limited to air-cooled radiators, but also passive air-cooled fins, liquid cooling, compressors, etc.) There are bound to be some differences in the effect in actual use, which cannot be generalized and should be analyzed according to specific circumstances.

So how should we judge the test results of OCER.net? We will explain in detail in a later test report.

    This article introduces the thermal resistance of the heat sink, and the wind resistance knowledge will be introduced in the next article, looking forward to it!