Gelid Solutions Gelid Silent 12 Pwm 120Mm Pwm Fan-1500 Rpm Max 12-25. Designed for advanced users GELID Silent PWM fans provide additional airflow by using Pulse Width Modulation (PWM) to automatically adjust fan speed according to the CPU load. The fan can be idled down and thus be much quieter. An intelligent IC had been integrated into the fan’s PCB to exploit your mainboard’s BIOS software. This technology is more efficient and convenient than using an external fan controller to adjust the voltage. Each fan impeller has been individually balanced using the latest technology to guarantee steady, unwavering operation. To add to the silence fan mounts replace traditional screws and are made of high quality, temperature resistant, extra long lasting rubber and stop vibrations from the fan motor from traveling into your PC case.