A PWM hub is a splitter used for connecting and synchronized control of multiple computer fans. It is used in cases where the computer's motherboard does not have enough connectors for all the fans in the case. The entire hub connects to a single 4-pin fan connector on the motherboard. From this connector, it receives a control signal known as PWM (Pulse Width Modulation), which is a digital method for precise speed regulation. All fans connected to the hub then respond to this single signal and rotate at the same speed. Since a single connector on the motherboard could not power a large number of fans, the hub usually also has its own additional power supply, most often via a SATA connector directly from the computer's power supply. The motherboard then reads speed data from only one designated port on the hub and regulates the entire group of fans based on it.