To do that you need to:
Turn off the system, including any attached peripherals, and disconnect the system from the electrical
outlet. Then open up the system.
To remove the cooling shroud, release the blue latches on the shroud by pulling each latch outward
from its securing tab.
Lift the shroud straight up to disengage the fan connector from the system board, and then lift the
shroud out of the system.
If you want the instructions with pictures, please click the link below and refer to pages 79-80:Dell 2900 series Power Edge
It is in PDF format, if you can not open it please download and install free adobe reader by clicking this link:Adobe Reader