Dell Precision R5500 Owner's Manual page 26

2. Repeat step 1 for the remaining cooling fans.
3. Install the control panel.
4. Install the power supply.
5. Install the SAS backplane.
6. Install the hard drive assembly.
7. Install the hard-drive carrier.
8. Install the optical drive.
9. Install the cooling shroud.
10. Install the cover.
11. Install the front bezel.
12. Follow the procedures in
Related tasks
Removing the System Fans
26 System Fan
After Working Inside Your Computer.