New Power Policies in Windows 7

New Power Policies in Windows 7 for the Default (Balanced) Power Plan.

Another new feature of Windows 7 that improves energy efficiency is a unified architecture that drives the scheduling of both services and scheduled tasks and enables triggerstarting of services. For more information on this new unified architecture and on Trigger Start services, see the section titled "Understanding Services" later in this tutorial.

Windows 7 also allows you to run power efficiency diagnostics using the new /energy option of the Powercfg.exe command on a system to detect common energy efficiency problems. This command can detect power efficiency issues such as inefficient power policy settings, platform firmware problems, battery capacity issues, USB device selective suspend, and other problems. Enterprise system builders and OEMs can use this command option to validate the energy efficiency of Windows 7 computers prior to imaging them for deployment rollout. The command is also executed automatically when a Windows 7 system is idle and the data collected is uploaded to the Customer Experience Improvement Program (CEIP) at Microsoft. For information on how to use this new command option, see the section titled "Configuring Power Management Settings Using the PowerCfg Utility" later in this tutorial.

Other new energy efficiency features in Windows 7 include:

• Wake timers are now disabled by default on Windows 7 mobile computers to prevent spurious wake events, such as a system waking up in a laptop bag due to an application request. Wake timers will continue to be enabled by default, however, on desktop systems.
• You can now configure the percentage of battery capacity remaining that triggers the reserve power mode. This energy efficiency feature is also configurable by Group Policy; see the section titled "Configuring Power Management Settings Using Group Policy" later in this tutorial for more information.
• Adaptive Display Brightness can dim the display on a mobile computer automatically after a period of user inactivity. Adaptive Display Brightness is an intelligent policy whose time-out value automatically adjusts with user input and does not interfere with presentations, such as full-screen media playback. This energy efficiency feature is also configurable by Group Policy; see the section titled "Configuring Power Management Settings Using Group Policy" later in this tutorial for more information.
• Wired LAN run-time idle detection, whereby network interface cards can enter lowpower D3 (device sleep) state automatically when media is disconnected and return to D0 (working) state when it is reconnected.
• Wake on LAN (WoL), which is turned off by default in Windows Vista, is turned on by default in Windows 7. This feature uses a revised set of wake patterns to prevent spurious transitions from sleep.
• Support for the latest Intel HD Audio low-power specifications.
• Support for USB audio class selective suspend.
• Bluetooth radio now enters selective suspend when connections are in sniff mode.
• Updates to the core performance state algorithm.
• Core parking on supported hardware.
• Refined optical drive spin-down mechanism.