Micro Cooling Fan noisy factor

"Micro Cooling Fan" Speed is the number of revolutions per minute of the fan blades, the unit is rpm. Fan speed is determined by the motor inside the coil turns, operating voltage, the number of fan blades, angle, height, diameter and bearing systems. Speed and "Micro Cooling Fan" quality is not necessarily linked. Fan speed can be measured by the internal speed signal, it can also be measured by the external. Fan noise and friction, air flow related. Fan speed, the greater the amount of wind noise caused will be greater, additional fan vibration itself also can not be ignored. Of course, high-quality "Micro Cooling Fan" of the shock itself will be small, but the first two were, but it is difficult to overcome. To solve this problem, we can try to use larger size fan.