"Waterproof Cooling Fan" noise and friction, about the air flow. 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 a larger size "Waterproof Cooling Fan". Should be at the same air volume, a large fan operating noise at a lower speed is less than the operating noise small fan at high speed. Another factor is that we tend to ignore the fan bearings. Because "Waterproof Cooling Fan" To friction between the shaft and the bearing rotates at high speed collision, it is also a major source of fan noise.