Advanced Configuration and Power Interface (ACPI) is an open industry specification that defines a flexible and extensible hardware interface for the system board. Software designers use this specification to integrate power management features throughout a computer system, including hardware, the operating system, and application software. This integration enables Windows to determine which applications are active and handle all of the power management resources for computer subsystems and peripherals.
ACPI enables the operating system to direct power management on a wide range of mobile, desktop and server computers, and peripherals.
ACPI is the foundation for the OnNow industry initiative that allows system manufacturers to deliver computers that start at the touch of a key on a keyboard.
ACPI design is essential to take full advantage of power management and Plug and Play in Windows. If you are not sure whether your computer is ACPI-compliant, check your manufacturer's documentation. To change power settings that take advantage of ACPI, use Power Options in Control Panel.
During Windows Setup, ACPI is installed only if all components present during Setup support power management. Some components, especially legacy components, do not support power management and can cause erratic behavior with Advanced Power Management (APM), or may prevent ACPI from being installed. Examples of such components are Industry Standard Architecture (ISA) components and an out-of-date BIOS.