The fans can work in the intelligent mode or forcible mode.

In the intelligent mode, the fans start to operate only when the ambient temperature goes higher than a specified value. In V200R003C00 and later versions, you can run the display fan speed-adjust threshold minus command on the switches that use the intelligent heat dissipation mode to view the temperature thresholds for the fans to start and stop running. The set fan speed-adjust threshold minus command can be used to lower these temperature thresholds.

S5700 models corresponding to intelligent heat dissipation mode