Service manual

System Overview 1-37
Description
One to three power supplies provide power to components in the system drawer.
(They supply power only for the drawer in which they are located.) Three power
supplies provide redundant power in fully loaded AlphaServer 4000/4100 systems.
These power supplies share the load, and redundant configurations are supported.
They autoselect line voltage (120V to 240V). Each has 450 W output and supplies
up to 75A of 3.43V, 50A of 5.0V, 11A of 12V, and small amounts of –5V, –12V,
and auxiliary voltage (Vaux).
NOTE: The LEDs on some modules are on when the line cord is plugged in,
regardless of the position of the On/Off button.
Configuration
• An AlphaServer 4100 system with one or two CPUs requires one power supply
(two for redundancy).
• An AlphaServer 4100 system with three or four CPUs requires two power
supplies (three for redundancy).
• An AlphaServer 4000 system with one or two CPUs and one PCI card cage
requires one power supply (two for redundancy).
• An AlphaServer 4000 system with one or two CPUs and two PCI card cages
requires two power supplies (three for redundancy).
• Power supply 0 is installed first, power supply 2 second, and power supply 1
third. See Figure 1-22. (The power supply numbering shown here corresponds to
the numbering displayed by the SRM console's show power command.)