The PWM signal input from the mainboard is used to control a series of connected PWM fans for optimal performance in noise and cooling. Connect two PWM fans to your mainboard's CPU socket. Use multiple Y cables to connect a series of up to five PWM fans and provide as much extra cooling as desired. Power drawn into your CPU cooler is adjusted depending on its temperature. An idle CPU does not generate as much heat, requires less active cooling and hence slower fan speeds will be sufficient. Furthermore, this also reduces the overall ambient noise of your PC and it is handled automatically with little risk to your PC components. While PWM fan controllers are very common in today's PC industry and available on most mainboards, there is often only one or two such PWM headers reserved for the CPU and or the chipset fans. One way this excellent noise reduction idea can be extended to the numerous case fans inside a typical PC is by utilising this Gelid PWM Y Cable. The 350mm long cable provides enough length to reach any location in your case.