Intel S845WD1-E manual System States and Power States, Effects of Pressing the Power Switch

Table 5 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 5.	Effects of Pressing the Power Switch
		…and the power switch is
If the system is in this state…		pressed for	…the system enters this state
Off		Less than four seconds	Power-on
(ACPI G2/G5 – Soft off)			(ACPI G0 – working state)
On		Less than four seconds	Soft-off/Standby
(ACPI G0 – working state)			(ACPI G1 – sleeping state)
On		More than four seconds	Fail safe power-off
(ACPI G0 – working state)			(ACPI G2/G5 – Soft off)
Sleep		Less than four seconds	Wake-up
(ACPI G1 – sleeping state)			(ACPI G0 – working state)
Sleep		More than four seconds	Power-off
(ACPI G1 – sleeping state)			(ACPI G2/G5 – Soft off)

System States and Power States

Under ACPI, the operating system directs all system and device power state transitions. The operating system puts devices in and out of low-power states based on user preferences and knowledge of how devices are being used by applications. Devices that are not being used can be turned off. The operating system uses information from applications and user settings to put the system as a whole into a low-power state.

Table 6 lists the power states supported by the S845WD1-E board along with the associated system power targets. See the ACPI specification for a complete description of the various system and power states.

Table 6. Power States and Targeted System Power

			Processor		Targeted System
Global States	Sleeping States		States	Device States	Power (Note 1)
G0 – working	S0	– working	C0 – working	D0 – working	Full power > 30 W
state				state.
G1 – sleeping	S1	– Processor	C1 – stop	D1, D2, D3 –	5 W < power < 52.5 W
state	stopped		grant	device
				specification
				specific.
G1 – sleeping	S3	– Suspend to	No power	D3 – no power	Power < 5 W (Note 2)
state	RAM. Context			except for
	saved to RAM.			wake-up logic.
G1 – sleeping	S4	– Suspend to	No power	D3 – no power	Power < 5 W (Note 2)
state	disk. Context			except for
	saved to disk.			wake-up logic.

continued

Description 29