Acer AcerAltos 21000 System Manual page 38

Right Panel
The power subsystem fills up most of the rear right panel. It consists
of a power backplane board and a metal rack that holds up to three
430-watt redundant power supply modules. A fan module should be
installed whenever a power supply is removed to provide the system
with regular cooling.
subsystem.
The lower section allows installation of a SCSI backplane board and a
set of eight hot-swappable SCSI drive trays.
Here is a diagram of the components that reside on the right panel.
SCSI Drive Tray
Bays
System Housing
See section 2.5 for details on the power
Power Supply
Module Bays
Power Supply
Backplane Board
SCSI Backplane
Board
2-13