The rotational speed of the cooling fan is determined by the voltage, the angle of the fan blades, the diameter, the number of the fan blades, bearings, etc. . So what causes the Cooling Fan to slow down? The main conditions that determine the rotating speed of the cooling fan are the structure of the fan itself and its parts, the friction of the bearing and the wind resistance of the inclination of the Fan Blades, such as wind sand, high and low temperatures and other adverse circumstances will also affect the cooling fan rotating speed slow, 2, check whether the cooling fan is used for a long time, did not clean up, because the accumulation of more dust or impurities, make the fan operation is more difficult, resulting in slow speed, 3, check whether the cooling fan is installed, not installed in the loose situation will also make the fan speed slow. The above is what causes the cooling fan rotating speed to slow down introduced by Dong Xingyue. A good cooling fan is very important. It can not only make the equipment run normally, but also prolong its service life and increase its working efficiency, if you want to know more about the cooling fan knowledge can follow us.