The EK-Cable Splitter 4-Fan PWM Extended is a 1-to-4 PWM fan splitter that allows the user to connect up to four PWM fans from a single PWM fan header on the motherboard. And because the fans are controlled by PWM, the RPM of each fan will change according to the CPU temperature and/or the motherboard's BIOS settings, which means that the RPM and therefore the noise will be reduced if the system does not require high airflow.