But what would happen if we slow the fans down? In that case, the liquid temperature, or the ΔT, would rise from 10°C to, let’s say 15°C. Now here is the twist. If the temperature of the liquid rises inside the radiator and the ambient temperature remains the same, the radiator will have a greater cooling capacity. Higher liquid temperature means the radiator becomes more efficient and can remove more heat. At the same fan speed (1800 RPM) with the liquid temperature at 15°C higher than the ambient temperature, the same 240mm XE radiator could remove around 500W of heat. This means that you can have less noisy fans and get slightly higher CPU and GPU temperatures.

If you are having a hard time understanding this, imagine that the greater the difference between the ambient temperature and the liquid temperature, the more efficient the radiator gets. For the same reason, a fairly „small“ car radiator can cool the engine, because it has its liquid temperature at 90°C and the ambient temperature is mainly 25°C during the spring. If you are still having a hard time understanding all this, just know that the bigger the W/10°C number is, the better the cooling capacity of the radiator is.

So finally, let’s compare some radiators. Here is a performance comparison of the EK-CoolStream SE 240 26mm thick radiator with an FPI of 22, EK-CoolStream PE 38mm thick radiator with an FPI of 19, and the EK-CoolStream XE 60mm thick radiator with an FPI count of 16.