ACPI

Intel® NUC 12 Extreme / Pro X

ID	Date	Version	Classification
721073	02/24/2022	1.0	Public

ACPI gives the operating system direct control over the power management and Plug and Play functions of a computer. The use of ACPI with this 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 a front panel power and sleep mode switch

Table 3 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 3. Effects of Pressing the Power Switch

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

Note: Depending on power management settings in the operating system.

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 into a low-power state.

Table 4 lists the power states supported by the board along with the associated system power targets. See the ACPI specification for a complete description of the various system and power states.

Table 4. Power States and Targeted System Power

Global States	Sleeping States	Processor States	Device States
G0 – working state	S0 – working	C0 – working	D0 – working state.
G1 – sleeping state	S3 – Suspend to RAM. Context saved to RAM.	No power	D3 – no power except for wake-up logic.
G1 – sleeping state	S4 – Suspend to disk. Context saved to disk.	No power	D3 – no power except for wake-up logic.
G2/S5	S5 – Soft off. Context not saved. Cold boot is required.	No power	D3 – no power except for wake-up logic.
G3 – mechanical off AC power is disconnected from the computer.	No power to the system.	No power	D3 – no power for wake-up logic, except when provided by battery or external source.

Notes:

Total system power is dependent on the system configuration, including add-in boards and peripherals powered by the system chassis’ power supply.
Dependent on the standby power consumption of wake-up devices used in the system.

Wake-up Devices and Events

Table 5 lists the devices or specific events that can wake the computer from specific states.

Table 5. Wake-up Devices and Events

Devices/events that wake up the system…	…from this sleep state	Comments
Power switch	S3, S4, S5¹
RTC alarm	S3, S4, S5¹	Monitor to remain in sleep state
LAN	S3, S4, S5^{1, 3}	“S5 WOL after G3” must be supported; monitor to remain in sleep state
WIFI	S3, S4, S5^{1, 3}	Monitor to remain in sleep state
Bluetooth	S3¹, S4
USB	S3, S4, S5^{1, 2, 3}	Wake S4, S5 controlled by BIOS option (not after G3)
PCIE	S3, S4	Via WAKE; monitor to remain in sleep state
HDMI CEC	S3, S4, S5¹	Emulates power button push

Notes:

1. S4 implies operating system support only.

2. Will not wake from Deep S4/S5. USB S4/S5 Power is controlled by BIOS. USB S5 wake is controlled by BIOS. USB S4 wake is controlled by OS driver, not just BIOS option.

3. Windows Fast startup will block wake from LAN and USB from S5.

NOTE

The use of these wake events from an ACPI state requires an operating system that provides full ACPI support. In addition, software, drivers, and peripherals must fully support ACPI wake events.