"Mini Air Cooling Fan" noise and friction, air flow related. Fan speed, the greater the amount of wind noise will be greater due to another fan's own shock factor can not be ignored. Of course, high-quality fans will shake itself is small, but the first two were, but it is difficult to overcome. To solve this problem, we can try to use larger size "Mini Air Cooling Fan". Should be in the same amount of wind, the big fan operating noise at low speed is less than the work of a small fan noise at high speed. Another factor is that we tend to ignore the fan bearings. Due to the high-speed rotation of the fan to be friction between the shaft and bearing a collision, it is also a major source of "Mini Air Cooling Fan" noise.