HP EliteDesk 800 G3 SFF Hardware Reference Manual page 12

Removing the computer access panel
To access internal components, you must remove the access panel.
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 and lay the computer down.
6. Slide the access panel release lever to the left (1) so that it locks into place. Then slide the access panel
back (2) and lift it off the computer (3).
6 Chapter 2 Hardware upgrades
Regardless of the power-on state, voltage is always present on the system board as long