Many Corsair power supplies feature cooling fans with Zero RPM technology. Essentially, while the power supply is at lower loads and producing less heat, the intake fan is stopped, therefore producing zero noise. As the load on the PSU increases, the power supply produces more heat and that heat needs to be evacuated. A thermistor inside the power supply tells the fan to kick on. Once those temperatures drop to a level that is safe for the power supply to operate without active cooling, the fan cuts off and the power supply runs silently once again.
For my demonstration, I will be using an AX Series AX860i Digital ATX PSU and Corsair Link software to demonstrate how the PSU’s power output and temperatures increase with load, and how the power supply fan speed increases and decreases with that temperature.