"220V Cooling Fan" depends mainly on the fan shape, size, height and speed. Blade shape design, size, height effects are more complex, will be explained later; the faster fan speed, the faster the wind speed, it is obvious common sense, needless to say. "220V Cooling Fan" will affect the level of wind speed and the size of the wind noise. The same area had wind, wind speed, the greater the amount of wind; between airflow, friction will air fan, frame, between the fins of the noise, the same fan, heat sink design, noise is bound with wind speed The upgrade increases. As the general and not as a performance parameter "220V Cooling Fan" products are marked, the user selects the fan will not see, not to mention the precautions.