There are many advantages of using PWM control over other methods. The main advantage with regards to fan life is that the electrical components are supplied with constant voltage and power. The PWM response curve allows for users to customize a slope that best suits their needs. For example, users can have the fan turn off completely at 0% duty, or choose to have it spin at a low speed to offer minimal cooling at 0% duty.  PWM controllers also easily allow the user to individually control fans in a system if required.