"Waterproof Cooling Fan" PWM Speed: PWM speed can be manufactured, this function automatically adjusts the DC cooling fan rotation speed, when the ambient temperature is low, DC cooling fan running at low speed state, when high ambient temperature operation when, "Waterproof Cooling Fan" is running in a high speed condition, however, this function is necessary to achieve with 4Pin, one of which is a line of information to adjust the PWM and FG .RD alarm signal: producing FG signal output, the signal FG is a major role for equipment "Waterproof Cooling Fan" speed, as well as abnormal when turning or stopping the blower, the signal line output high voltage signal back to the motherboard alarm.