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A Power System: Description/CalculatingPower Usage
This appendix describes the modular power system and explains how to calculate power usage for
your server.
WARNING
Only a QUALIFIED SERVICE TECHNICIAN is authorized to remove
the server covers and to access any of the components inside the server.
Before removing the covers, see “Safety: Before You Remove Server
Covers” on page 93 and “ Warnings and Cautions” on page 94.

Power System

The modular power system for the server is provided by up to three 750 watt autoranging power
supplies and a midplane. The power system may be configured with two power supplies
(standard) or three power supplies (2 + 1, redundant). The power supplies are mounted in a
2 + 1 pattern in the back of the chassis along the bottom. Each power supply has an integrated fan
for cooling.
The midplane provides connectors for the hot-swap power supplies. The midplane also provides
the interface logic for power supply related management functions such as
• Power supply presence detection.
• Power supply fault signal reporting.
Care must be taken not to overload a branch circuit of the AC mains by plugging too many power
cords into a single AC circuit. We recommend plugging the power cord of the server into a
separate circuit.
If a power supply fails in the redundant power system, the yellow power supply failure LED on the
front panel starts flashing. The supply can be hot-swapped—removed and replaced—without
turning off the power or impacting server operations (providing that 3 power supplies are installed.