FOCUS PLUS Fan Control Button
The fan control button can be found on the back of the back of the FOCUS PLUS power supply, next to the power switch. The image here illustrates how to select different fan control modes to suit your need.
DO NOT press the button if you wish to include the Fanless Mode, which means the fan in the power supply will not spin when the power supply is under light loads. Press the button if you wish to have the fan spin at all times, even at lower loads.