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

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