[ Thanks to Mike
Weber for this link. ]
“ACPI provides the interface on both workstations and servers to
shutdown automatically when requested. It is also used by power
management to extend battery life by working with the operating
system as well as the BIOS. This provides greater flexibility for
responding to power events which may be initiated by the operating
system or user.“Since Microsoft was the first vendor to implement ACPI, many
BIOSs are configured to meet Microsoft ACPI standards but may not
be as effective when the computer has Linux installed on it.”