The NorthPole XE whisper cooler fan is heat-controlled, meaning that its voltage is regulated on the basis of the cooler’s working temperature. The fan used is a standard fan measuring 40x40x15mm (Delta AFB0412LB). A customised electronic board has been added to it in order to regulate its voltage between 5V and 12V on the basis of the temperature recorded above the copper cooler fins. The fan, which normally rotates at 5000 r.p.m. at 12V, is therefore made to run at a lower speed, with noise emission of around 14dB.

NorthPole XE whisper and a detail of the heat-controlled fan

When the system is idle, Pentium M processors and Northbridges consume far less energy, taking the cooler temperature to just a few degrees above room temperature, with a fan speed of between 1500-2500 r.p.m. When the system is in use, the temperature increases, especially if the motherboard is housed in a small compartment, as is often the case for HTPCs. In these conditions, the fan voltage rises, taking the rotation speed to around 2500-4000 r.p.m.

The diagram extension the relationship between the temperature recorded from the probe and the voltage of exercise of the fan.

A solution of this kind makes it possible to keep the overall system temperature down, despite using the fans at a reduced rotation speed. This consequently means that the total noise produced is well below.