Powercfg is a command-line utility for configuring Windows 7 power management policy. Powercfg.exe exposes all power management settings, including those that are not available in the UI or from Group Policy.
Power management settings are represented by GUIDs, so using Powercfg.exe generally requires that you know the GUIDs for the settings you want to modify. However, Powercfg.exe also supports aliases for most common GUIDs. To display a list of supported aliases, type:
In Windows 7, the Powercfg utility has been enhanced with a new command-line option: /energy. This can be used to detect common energy-efficiency problems, such as excessive processor utilization, increased timer resolution, inefficient power policy settings, ineffective use of suspend by USB devices, battery capacity degradation, and more. You can use this option to validate a system or configuration prior to deployment, provide support to users who encounter battery life or power consumption issues, or even diagnose energy-efficiency problems on your personal system.
In addition, a new /requests option for the Powercfg command lets you enumerate application and driver requests that prevent the computer from automatically turning off the display or entering Sleep mode. And a new /requestsoverride option for the Powercfg command lets you override either individual availability requests or all availability requests.