"220V Cooling Fan" noise and friction, air flow related. Fan speed, the greater the amount of wind noise will be greater due to additional fan vibration itself also can not be ignored. Of course, the fan itself high quality shock will be small, but the first two were is difficult to overcome. To solve this problem, we can try to use larger size "220V Cooling Fan". Should be under the same amount of wind, the big fan operating noise at low speed to less than a small fan operating noise at high speed. Another factor is that we tend to ignore the fan bearings. Because "220V Cooling Fan" to friction between the shaft and the bearing is rotated at a high speed collision, it is also a major source of fan noise.