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1.12 Power Management
Power management is implemented at several levels, including:
•
Software support through Advanced Configuration and Power Interface (ACPI)
•
Hardware support:
⎯ Power connector
⎯ Fan headers
⎯ LAN wake capabilities
⎯ Instantly Available PC technology
⎯ Wake from USB (S1 and S3 only)
⎯ Power Management Event signal (PME#) wake-up support
⎯ WAKE# signal wake-up support
⎯ Wake from PS/2 device
⎯ Wake from serial port
1.12.1
ACPI
ACPI gives the operating system direct control over the power management and Plug
and Play functions of a computer. The use of ACPI with the board requires an
operating system that provides full ACPI support. ACPI features include:
•
Plug and Play (including bus and device enumeration)
•
Power management control of individual devices, add-in boards (some add-in
boards may require an ACPI-aware driver), video displays, and hard disk drives
•
Methods for achieving less than 15-watt system operation in the power-on/standby
sleeping state
•
A Soft-off feature that enables the operating system to power-off the computer
•
Support for multiple wake-up events (see Table 10 on page 35)
•
Support for a front panel power and sleep mode switch
Table 8 lists the system states based on how long the power switch is pressed,
depending on how ACPI is configured with an ACPI-aware operating system.
Table 8. Effects of Pressing the Power Switch
If the system is in this
state...
Off
(ACPI G2/G5 – Soft off)
On
(ACPI G0 – working state)
On
(ACPI G0 – working state)
Sleep
(ACPI G1 – sleeping state)
Sleep
(ACPI G1 – sleeping state)
...and the power switch
is pressed for
Less than four seconds
Less than four seconds
More than four seconds
Less than four seconds
More than four seconds
Product Description
...the system enters this state
Power-on
(ACPI G0 – working state)
Soft-off/Standby
(ACPI G1 – sleeping state)
Fail safe power-off
(ACPI G2/G5 – Soft off)
Wake-up
(ACPI G0 – working state)
Power-off
(ACPI G2/G5 – Soft off)
33
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