Compaq 247320-003 - Deskpro 4000 - 5166 Model 2500/CDS Reference Manual page 222

To change the system board switch module, you must
remove the computer cover or side panel. For information
about removing the computer cover or side panel, refer to
Chapter 6, "Upgrading the Desktop Computer," or
Chapter 7, "Upgrading the Minitower Computer."
!
The computer is shipped with the power-on password feature
enabled. To disable the power-on password, set S1 on SW1 to
On.