User`s manual

5
Board Requirements and Parameters
This chapter describes the Alpha PCI 64–275 power and environmental
requirements and physical board parameters.
5.1 Power Requirements
The Alpha PCI 64–275 derives its dc power from a user-supplied, industry-
standard PC power supply. The board has a total power dissipation of 96.2 W,
excluding PCI and ISA devices. Table 5–1 lists the power requirements of each
dc supply voltage.
The power supply must supply signal p_dcok to the board reset logic.
Table 5–1 Power Supply dc Current Requirements for Motherboard (275 MHz)
Without I/O
Voltage Current
+5 Vdc 10 A (maximum)
+3.3 Vdc 10 A (maximum)
–5 Vdc 0 A
+12 Vdc 1 A (maximum)
–12 Vdc 0.1 A (maximum)
These values do not include power requirements for peripherals such as disks and
tapes. You must increase the power supply capacity to meet the requirements of any
peripherals you add.
Caution: Fan Sensor Required
The cooling fan supplied with the Alpha PCI 64–275 has a built-in
sensor, connected to J14, that drives a signal low while the fan spins.
Board Requirements and Parameters 5–1