Technical Reference
61
2.5
Electrical Considerations
2.5.1
Power Supply Considerations
CAUTION
The +5 V standby line from the power supply must be capable of providing adequate
+5 V standby current. Failure to do so can damage the power supply. The total
amount of standby current required depends on the wake devices supported and
manufacturing options.
Additional power required will depend on configurations chosen by the integrator.
The power supply must comply with the indicated parameters of the ATX form factor
specification.
•
The potential relation between 3.3 VDC and +5 VDC power rails
•
The current capability of the +5 VSB line
•
All timing parameters
•
All voltage tolerances
For example, for a system consisting of a supported 65 W processor (see Section 1.4
on page 14 for a list of supported processors), 1 GB DDR2 RAM, one hard disk drive,
one optical drive, and all board peripherals enabled, the minimum recommended
power supply is 85 W. Table 24 lists the recommended power supply current values.
Table 25. Recommended Power Supply Current Values
Output Voltage
3.3 V
5 V
12 V1
12 V2
-12 V
5 VSB
Current
4.06 A
8.00 A
2.54 A
2.50 A
0.04 A
0.14 A
2.5.2
Fan Header Current Capability
CAUTION
The processor fan must be connected to the processor fan header, not to a chassis fan
header. Connecting the processor fan to a chassis fan header may result in onboard
component damage that will halt fan operation.
Table 26 lists the current capability of the fan headers.
Table 26. Fan Header Current Capability
Fan Header
Maximum Available Current
Processor fan
2.0 A
Chassis fan
1.5 A