The ECO Thermal Control System, when enabled, allows the fan on your EVGA power supply to "NOT Rotate" during low to moderate operation loads. The EVGA power supply's fan will automatically turn back on, when needed, based on the temperature the power supply reaches. The fan will also increase in RPM when needed based on the load operation being requested from the components connected. This prevents unnecessary rotation in order to increase the life span of the fan due to the power supply's high efficiency it offers.
Turning this feature off, the fan will always spin, even at low loads and the fan will also increase in RPM when needed automatically based on the load operation being requested from the components connected.
Please see our overview video for more details on the functionality of this feature demonstrated in the video: