Compaq 247320-003 - Deskpro 4000 - 5166 Model 2500/CDS Reference Manual page 90

The slide-out drive cage allows access to all drive bays for easy
installation of additional drives, with no drive rails or brackets
required. With the drive cage pulled out from the chassis, you
can easily connect the drive power and signal cables.
When installing optional drives, you must install one
guide screw to ensure the drive will line up correctly in
the drive cage. Compaq has provided extra guide screws,
installed in the front of the computer chassis, under the
front bezel.
To slide out the drive cage, follow these steps:
1. If you have locked the Smart Cover Lock, use Computer
Setup to unlock the lock.
For more information about Computer Setup, refer to
Chapter 8, "Using Compaq Utilities."
2. Turn off the computer and any external devices.
3. Disconnect the power cord from the power outlet.
4. Remove the computer cover and front bezel.
5. Remove the two screws securing the drive cage to the front
of the computer chassis.