"Mini Air 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, inclination, height, diameter and bearing systems. Fan speed and quality are not necessarily linked. The fan speed can be measured by the internal speed signal can also be measured by an external (external measure is to look at how fast the fan speed with the other instruments, internal measurements directly to the BIOS can see, you can also look through the software. Internal Some relatively large measurement error).