The f12 pwm features PWM function for regulating the fan speed, the ARCTIC PWM 120mm fan runs at the appropriate RPM to deliver maximum cooling capacity at the lowest noise level possible. In addition, the patented and innovative PWM Sharing Technology (PST) controls up to 5 fans via the BIOS in your system for maximum cooling and efficiency. When the system load increases, fan speed of all fans connected in the PST system will be increased in order to lower the case temperature. Likewise, when the load is low, these fans will operate at a relatively low speed for sufficient cooling. Get this smart fan technology today and keep your system cool. Arctic Cooling AF12 PWM F12 120 mm PC Computer Case Fan (AF12PWM) .