A fixed "Micro Cooling Fan" structure, the DC fan (ie using DC fan) with the operating speed of the change in voltage synchronous changes. The fan speed can be measured by the internal speed signal can also be measured (external measurement is to measure fan speed speedometer with a special red line through the outside, internal measurements directly to the BIOS can see, "Micro Cooling Fan" can also be Look through the software. Internal measuring relatively large number error). Distinguish Powerful and silent type is not too strict, but the same size, with a voltage of a computer fan, the wind pressure and noise will always be two irreconcilable contradictions. "Micro Cooling Fan" is the number of times the speed of rotation of the fan fan pages per minute, the unit is rpm. Speed is determined by the motor inside the coil turns, voltage, number of fan fan pages, inclination, height, diameter and fan bearing system.