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This article describes the default behavior of a Windows Vista-based desktop computer when you wake it from sleep and when it wakes up automatically. Additionally, the article introduces some power management tools. The computer may run better if you use these tools.
System power states in Windows VistaThe behavior of a Windows Vista-based desktop computer when it wakes up from sleep does not depend on how it went to sleep.
Windows Vista uses the following four power states:
System power state S1System power state S1 is a sleep state. This power state has the following characteristics:
System power state S2System power state S2 is a sleep state. System power state S2 resembles system power state S1. However, in system power state S2, the CPU context and contents of the system cache are lost because the processor loses power.
This power state has the following characteristics:
System power state S3System power state S3 is a sleep state. This power state has the following characteristics:
System power state S4System power state S4 is the hibernate state. System power state S4 is the lowest-powered sleep state. Also, system power state S4 has the longest wake-up latency.
For more information about these system power states, visit the following Microsoft Web site:
Sleep states and the monitorAfter you put the computer in the hibernate state, Windows Vista automatically turns off the monitor. The computer wakes up, and Windows Vista turns on the monitor when one of the following events occurs:
After you put the computer in a sleep state other than the hibernate state, Windows Vista automatically turns off the monitor. The computer wakes up when one of the following events occurs:
Power management toolsYou can use the Powercfg tool to control the computer's power settings. To view the current power configuration, run the powercfg -q command at a command prompt.
You can also test the computer configuration and the computer's response to different system power states. To do this, use the power management test tool (PwrTest.exe). PwrTest.exe is included in the Microsoft Windows Driver Kit (WDK). After you install Microsoft WDK, PwrTest.exe is in the Tools\Acpi\PwrTest folder. To view Help, run the Pwrtest /? command at a command prompt.
For more information about the power management test tool, visit the following Microsoft Web site:
Away modeAway mode is a new feature in Windows Vista that is designed for Media Center computers. When a computer is in away mode, Windows Vista turns off the display and mutes the analog audio. If you turn away mode off, the computer goes to sleep after the computer is idle for two minutes.
When the computer goes back to sleepAfter the computer wakes up, the computer goes back to its previous sleep state if the computer is idle for a certain time. For example, this behavior may occur after the computer wakes up to automatically install a Windows update.
Article ID: 937556 - Last Review: October 31, 2007 - Revision: 1.2