When if "Tiny Cooling Fan" rotor inertia physical centroid and the center of the rotor shaft axis is not the same, it will cause the rotor imbalance. Recently physical centroid distance and the shaft center of inertia of the rotor is called the eccentricity of the rotor does not cause eccentricity not balanced, when the rotor is rotated due to the centrifugal force generated in the shaft mount and a force of vibration is formed, and the vibration is transmitted to the base path via various parts of machinery. "Tiny Cooling Fan" only pure wind noise sounds of the wind, and abnormal sound is different, when the fan is running, in addition to the wind, but if there are other sound, you can determine the fan has different tone. "Tiny Cooling Fan" abnormal noise may be due to the bearing of a foreign body or deformed, and improper assembly of a collision, or the motor winding is wound unevenly, resulting in loose, are likely to produce different sounds.