Dell Precision T3400 (Late 2007) - Manual (Page 211)

Adding and Replacing Parts
211
To remove the fan:
1 Disconnect the fan cable from the fan and from the fan connector on the
system board.
2 Press in on the fan release tab and lift to remove the fan.
1 fan slots (3) 2 fan release tab
3 fan cable 4 fan connector on system board
5 power supply
5
4
3
2 1