Power Management on Linux, Part 2 - page 2
Five Degrees of Laptop OffAPM (Advanced Power Management) is the old power management daemon and utilities for Linux. It's simple and easy, and it leaves most of the power management to your system BIOS. The modern replacement is ACPI (Advanced Configuration and Power Interface). The ACPI standard has several advantages over APM: it puts control of power management in the operating system instead of the system BIOS, and it handles events like slow and idle states in different components. For example, Intel led the way in dynamic CPU power management, and now both Intel and AMD CPUs scale their power needs according to demand. Network interfaces, video cards, and hard drives that support going into idle states can all be managed by ACPI.
ACPI is well-supported by Windows, which translates into wide ACPI support. Which can also a source of problems, because of Microsoft's famous habit of implementing standards in their own non-standard ways, but these days some laptop manufacturers actually test for ACPI compliance on the major Linux distributions. Amazing and true. As always, shop carefully, and if it means spending a few more dollars to get a machine that works well with Linux, it's money well-spent, because it means you're buying better-quality hardware. Those bargain Winmachines are cheap through and through, and they use a lot of shoddy Windows hacks as substitutes for good hardware. Lenovo Thinkpads and ASUS are my favorites (ASUS even has free recycling). Toshiba and Fujitsu laptops are good-quality and Linux works well on them too.