The Advanced Configuration and Power Interface was developed as an industry standard by several computer hardware and software manufacturers in 1996. The purpose of ACPI is to let the hardware and software manage the power usage of computers through such tools as sleep, hibernation and Wake-on-LAN.
1Access the BIOS: In order to change some of the ACPI settings you must access the basic input/output system on the computer. Typically computers will display a key or key combination that must be pressed as the computer boots up to access the BIOS, which may also be referred to as the "Setup" on some systems. If you don't see the key you need to press you may be able to find it listed online (link in Resources). Once you have accessed the BIOS, the ACPI settings will be in the power section. Some options may be labeled ACPI, but the title doesn't refer to the options but the standard for the options. Things like suspending the computer to RAM, entering into hibernation or waking the computer by a signal from a network card are all a part of the ACPI specification.
2Sleep Modes: The ACPI specification allows for several different operating states for computers. Fully powered on and running uses the normal amount of power. Within the sleep states the hard drive can be powered down while the computer remains active, the CPU can be powered down while the RAM is maintained, or the information in the RAM can be saved to the hard drive and the system will hibernate. The lower the sleep mode the less power the computer uses but the longer it takes to come back after sleep. Sometimes devices or programs can interfere with sleep modes and the ACPI settings need to be disabled to allow the devices to continue to run properly.
3Wake-on-LAN: Most of the time Wake-on-LAN is used in office environments where the IT team needs to turn on computers remotely to perform diagnostics or software upgrades. This setting uses the ACPI specification to keep a small amount of power running to the network card so that when it receives the right signal the computer can be powered on.
4Powering Up: You can also use the BIOS to define when and how the computer boots up in different circumstances. If you want to have your computer come on at a specific time each day you can set the Automatic Power Up feature to On. You can determine how the computer reboots if there is a power loss or set it to boot up if it detects input from a mouse or keyboard. One key for using ACPI settings in the BIOS is that all the hardware and software needs to work together. If some of the features aren't working correctly then it might be necessary to disable the feature or switch out the hardware.