When "Small Cooling Fan" of temperature change is slow, the cooling fan speed changes are slow, will not suddenly change the cooling fan speed and noise. The reaction time depends mainly on the length of the sensor of its thermally-induced sensitivity. So "Small Cooling Fan" The speed of the main basis for the control of the temperature difference between the heat sink induction passed automatically adjust. DC motor stator and rotor of two parts, there is the stator poles (windings or permanent magnet), rotor windings, the power, the rotor has a magnetic field (magnetic), "Small Cooling Fan" stator and rotor poles there is an angle between the rotor and stator magnetic field in operation (N and S poles between) the mutual attraction.