"Micro Cooling Fan" noise and friction, air flow related. DC fan speed, the greater the amount of wind noise caused by the greater will be the other DC fan vibration itself also can not be ignored. Of course, high-quality "Micro Cooling Fan" shake itself will be small, but the first two were is difficult to overcome. To solve this problem, we can try to use larger size of the DC fan. In the case of the same amount of wind, big DC fan noise at low speed work should be less than "Micro Cooling Fan" operating noise at high speed. Another factor is that we tend to ignore the DC fan bearings. Since DC fan speed rotation between the shaft and the bearing to friction and collision, it is also a major source of DC fan noise.