There are four main benefits:

1. Precision Control: Enables linear movement of the speed between 0-100, giving the exact amount of airflow required.
2. High Energy Efficiency: Operates at full power on demand only, and therefore has very low power usage at low loads, and would save much energy over fixed-speed fans.
3. Quiet Operation: Has the ability to reduce the speed to very low when the system is not being used or the system is lightly loaded, which significantly lowers the noise level.
4. Extended life: Since the PWM fan control is usually at a slower to medium speed most of the time, wear and tear against the motor and bearings is minimized, extending the total life of the fan.

A typical industry standard of control PWM fan signal frequency of PWM fans is 21kHz to 28kHz, and 25kHz is the most widely desired frequency.

The increased frequency banding is applied to ensure that the switching noise lies beyond the human audible frequency range so that a buzzing or whining sound is not heard when changing the speed.

The motor is better controlled by PWM. In voltage control, reduction of speed by reducing voltage may result in a lack of enough motor torque, more heat as well, and stalling at very low voltages.

PWM control, by contrast, guarantees to the motor a constant, full operating voltage–in pulses only. This ensures that the motor will never run out of torque to start and operate, and thus, a more stable operation and wear.

This is done by either a powered PWM fan hub or a PWM fan splitter. The single PWM signal of the host controller is transmitted to the splitter/hub, and the same is subsequently transmitted to all the attached fans, and as a result, all the fans can vary their speed simultaneously.

Key Considerations:

1. Tachometer Signal: The tachometer (speed) signal is typically simply transmitted by one assigned fan to the controller by most splitters and hubs. This will ensure that signal collision is avoided where several fans are reporting their speed at the same time.
2. Current: Make sure your power supply (e.g., the motherboard fan header) is capable of supplying the total starting and running current of all fans. A hub that has an external dedicated power connector is advisable for the majority of fans.
3. Fan Consistency: It is strongly advised to have the same model on all the fans attached to the hub in order to have the same performance.

Yes. This is one of the main merits of using PWM control.

The pulse width modulation fan itself is just an actuator that reacts to the PWM duty cycle it is fed by. The host controller (e.g., a BIOS of a server, a microcontroller, or a PLC) is programmed with the intelligence and the response curve. The thermal profile of any application can be perfectly adjusted with any control logic engineers want, whether linear, stepped, exponential, or a hysteresis loop, depending on sensor signals such as temperature, system load, or pressure.