One embodiment provides a system for controlling one or more pulse width modulated (PWM) fans. The system can include a control system configured to provide a voltage control signal corresponding to a DC output voltage for the one or more PWM fans. A variable DC voltage source is configured to supply the DC output voltage to the plurality of fans at one of at least two different DC voltages based on the voltage control signal. The DC output voltage from the variable DC voltage source is separate from a PWM control signal that is also supplied to the PWM fans.