HP Brio ba200 new power management for hp desktop pcs - Page 2

Why is Power Management Important? Power management is essential because it: • Helps cut power costs by reducing the amount of energy used by PCs • Allows the PC to meet and even exceed energy consumption regulations worldwide. APM Advance Power Management (APM) was the first major open industry standard developed to meet power management needs in personal computers. APM is controlled from the PC's BIOS. The BIOS establishes a connection with an operating system driver and in this way provides power management instructions to the operating system. APM was provided on all HP PCs, and has been successful in reducing the energy consumption of millions of PCs worldwide. However, the computing world has changed radically in the few years since APM was developed. Recent leaps in technology and new uses for PCs have rendered APM ill-equipped to deal with power management tasks. These emerging APM drawbacks include: • Difficulty in meeting the increasingly strict power saving regulations • Diminished availability. Computers are increasingly being used for demanding tasks requiring 24-hour availability. A PC that goes into an APM low power mode is unavailable for use and remains so until it has gone through the lengthy wakeup or startup procedure. Typically, there has been a strict trade-off between PC availability and the energy saving achieved. ACPI The latest technology is ACPI (Advanced Configuration and Power Interface). This is an open industry standard created by, among others, Microsoft and Intel. It addresses the drawbacks in APM and incorporates many improvements. Unlike APM, ACPI is controlled by the operating system. This allows easier control and configuration of power management (since the operating system is more accessible). ACPI also drastically reduces the trade-off between energy saving and PC availability. Now you can have 2 a PC that is available 24 hours a day, with highly reduced wakeup times, yet still save energy by using low power sleep modes. The specific advantages of ACPI over APM include: • New Hibernate mode This is a very low power consumption mode that also allows the PC to be quickly available. In Hibernate mode the PC appears to be switched off (power off). The PC system context is saved to hard disk and then reloaded (after the BIOS is initiated) for a fast wakeup. This is implemented in Windows 2000 and can be used in any recent or new HP PC. • Resistance to power failure The Hibernate mode is resistant to power failure as the OS state is saved to hard disk, so power out during Hibernation will not cause memory loss. The OS and current program states are saved until power is restored when the PC can automatically reload the last state and continue operation. • Suspend to RAM This is similar to the Hibernate mode described above, only there is less power saving and wakeup is faster, since the system context is saved in main memory. This is available on selected HP PCs. • Highly configurable Since control is centered in the operating system, you can configure ACPI power management parameters more easily. (APM is centered in the BIOS and requires you to restart the PC to configure power management.) ACPI also provides more features, with a wider range of configuration parameters, offering higher flexibility and greater user control. This is advantageous to both users and systems administrators (for desktop management tasks). • A configurable power switch This feature allows system administrators to choose what the PC does when the user presses the power switch. You can select very low power sleep states (Hibernate) or ultra-fast wakeup (Standby) for increased availability. This is discussed in "The Power Button and Unexpected Wakeup" on page 6. • More open to evolution The ACPI standard not only allows the operating system and hardware to perform coordinated power management, it also allows power management technology to evolve independently in the operating system and in the PC hardware.