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© Copyright IBM Corp. 2000 25
Chapter 4. Power supply
A 145-watt power supply drives your computer. The power supply provides 3.3-volt
power for the Pentium III microprocessor, core chip set, and 5-volt power for PCI
adapters. Also included is an auxiliary 5-volt (AUX 5) power supply to provide
power to power-management circuitry and a Wake on LAN adapter. The power
supply converts the ac input voltage into four dc output voltages and provides power
for the following:
• System board
• Adapters
• Internal drives
• Keyboard and auxiliary devices
• USB devices
A logic signal on the power connector controls the power supply; the front panel
switch is not directly connected to the power supply.
The power supply connects to the system board with a 2 x 10 pin connector.
Power input
The following table shows the power input specifications. The power supply has a
manual switch to select the correct input voltage.
Power output
The following figures show the power supply output of all the connectors, including
the system board, DASD, PCI, and auxiliary outputs.
The total combined 3.3 V and 5 V power must not exceed 100 watts.
Table 8. Power input requirements
Specification Measurements
Input voltage, low range 100 (min) to 127 (max) V ac
Input voltage, high range 200 (min) to 240 (max) V ac
Input frequency 50 Hz ± 3 Hz or 60 Hz ± 3 Hz
Table 9. Power output (145 watts)
Output voltage Tolerance Minimum current Maximum current
+5 V dc +5% to -5% 1.5 A 18.0 A
+12 V dc +5% to -5% 0.02 A 4.2 A
-12 V dc +10% to -10% 0.0 A 0.4 A
+3.3 V dc +5% to -5% 0.0 A 10.0 A
+5 V ac (auxiliary) +5% to -5% 0.0 A 0.720 A