HP Z1 Workstation - Manual (Page 21)

4. To access the lower I/O ports, carefully tilt the unit backwards, away from you.
Figure 3-3 Tilt the unit away from you to access the lower I/O ports
5. After tilting the unit, connect the power cord, Ethernet cable, and other peripherals, including the
wired keyboard and mouse, to the lower I/O panel.
Route the cables through or around the unit stand.
Figure 3-4 Connect cables to lower I/O panel
Setting up the workstation 13