Dell PowerConnect 8024 User Configuration Manual page 140

To change a 4 x 10G port to 1 x 40G mode, enter the following commands on
the 40-gigabit interface:
console(config)#interface Fo2/1/1
console(config-if-Fo2/1/1)#hardware profile portmode 1x40g
This command will not take effect until the switch is rebooted.
console(config-if-Fo1/1/2)#do reload
Are you sure you want to reload the stack? (y/n)
Attempting to change the port mode on the tengigabit interface will give the
error "An invalid interface has been used for this function."
140
Managing QSFP Ports