HP EliteDesk 800 G3 SFF Hardware Reference Manual page 32

Removing a 3.5-inch hard drive
NOTE: Before you remove the old hard drive, be sure to back up the data from the old hard drive so that you
can transfer the data to the new hard drive.
There are two 3.5-inch hard drive bays. The procedure for removing a 3.5-inch hard drive is the same for each
drive bay.
1. Remove/disengage any security devices that prohibit opening the computer.
2. Remove all removable media, such as compact discs or USB flash drives, from the computer.
3. Turn off the computer properly through the operating system, and turn off any external devices.
4. Disconnect the power cord from the AC outlet and disconnect any external devices.
IMPORTANT:
as the system is plugged into an active AC outlet. To prevent damage to internal components, you must
disconnect the power cord from the power source before opening the computer.
5. If the computer is on a stand, remove the computer from the stand.
6. Remove the computer access panel.
7. Disconnect the power cable (1) and data cable (2) from the rear of the hard drive.
26 Chapter 2 Hardware upgrades
Regardless of the power-on state, voltage is always present on the system board as long