HP ProLiant ML370 Generation 4 Reference And Troubleshooting Manual page 81

CAUTION: If only one power supply is installed, do not
remove the power supply unless the server has been powered down.
Removing the only operational power supply will cause an immediate
power loss.
1. Remove the T-15 Torx screws. Remove the power supply blank in the
secondary hot-plug power supply bay.
NOTE: The T-15 Torx screwdriver is clipped to the rear panel of the
server.
2. Install the second hot-plug power supply.
Hardware options installation 81