Dell DSS 2500 Owner's Manual page 88

Steps
1 Remove the fan cable connector from the system board by pressing the release tab on the system board end of the connector, and
lifting it away from the system board.
2 Release the cable from the cable holders on the fan bracket.
3 Press the release tab on the cooling fan and lift the fan away from the chassis.
Figure 35. Removing a cooling fan
1 cooling fans (6)
3 cooling fan cable connector
Next steps
1 If applicable, install the PCIe expansion card riser.
2 Reinstall the cooling shroud.
3 Follow the procedure listed in the After working inside your system section.
88 Installing and removing system components
2 cooling fan release tab
4 cooling fan connector on the system board