Many products require DC cooling fans more quiet, all sorts of design, more representative is the PWM function of DC cooling fan, this design is more quiet? Cooling fan PWM function of DC cooling fans, can use according to the product of high and low frequency of intelligence, adjust the speed of DC cooling fans, as we know, the higher the speed, the greater the wind, the better heat dissipation. And when we use frequency is low, the fan turned slowly, very quiet. As we play a game with a computer, use the CPU frequency is high, the cooling fan with PWM function is to spin faster, when we just use common office software, DC cooling fan is turned slowly, very quiet. So, DC cooling fan with PWM function designed to effect there is a mute, can bring more comfortable life.