On an SLX9540 shipped with five fans use of the sixth fan slot is not supported
On an SLX9540 shipped with five fans installed, an additional fan tray inserted in the sixth slot, on the far right when viewed from the back, is not recognized by the CLI. The status LED on the fan itself stays solid amber, and the fan spins at maximum speed.
In SLX9540s shipped with five fans, the sixth fan slot is disabled.
This is expected behavior. There is no method for enabling the sixth fan slot in the field.