Lenovo THINKSERVER 3821 - Manual (Page 185)

5. Connect one end of the power cord for the new power supply into the connector
on the back of the power supply; then, connect the other end of the power cord
to a properly grounded electrical outlet.
Note: If the server has been turned off, you must wait approximately 3 minutes
after you connect the server power cord to an electrical outlet before the
power-control button becomes active.
6. Make sure that the ac power LED on the top of the power supply is lit,
indicating that the power supply is operating correctly. If the server is turned on,
make sure that the dc power LED on the top of the power supply is lit also.
Installing redundant power supply and fans
You can install a second 920-watt hot-swap power-supply. This upgrade option
includes a hot-swap power supply and three hot-swap fans. You must also
purchase a second power cord to connect the power-supply to a power source.
To install the redundant power and cooling option, do the following:
1. Read the safety information that begins on page 5.
2. Remove the left-side cover (see “Removing the left-side cover” on page 157).
3. Remove the three fan air baffles 1 from the fan bays of the fan cage
assembly.
4. Install the three hot-swap fans 2 in the empty bays of the fan cage assembly.
Chapter 7. Installing optional devices and replacing customer replaceable units 177