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Power states in Windows

Power states in Windows

"Does anybody know or have a link to documentation on how the Power Manager of Windows, determines to go to the ACPI power states S1-S4? Are there any settings that can be configured? I know that by default states S1-S3 are disabled in Vista and later (they can be enabled by a group policy).
Can Windows cycle through these states while for instance an application is actively running?"

Asked by: Guest | Views: 62
Total answers/comments: 1
Guest [Entry]

"System Power States

To the user, the system appears to be either on or off. There are no other detectable states. However, the system supports multiple power states that correspond to the power states defined in the Advanced Configuration and Power Interface (ACPI) specification. The following table lists the power states from highest to lowest power consumption.



The system is fully usable. Devices
that are not in use can save power by
entering a lower power state.





The system appears to be off. Power
consumption is reduced to one of
several levels, depending on how the
system is to be used. The lower the
level of power consumption, the more
time it takes the system to return to
the working state.



The system appears to be off. Power
consumption is reduced to the lowest
level. The system saves the contents
of memory to a hibernation file,
preserving the state of the operating
system, applications, and open

Soft Off


The system appears to be off. Some
components remain powered so the
computer can wake from input from the
keyboard, LAN, or a USB device. The
working context can be restored if it
is stored on nonvolatile media.

Mechanical Off


The system is completely off and
consumes no power. The system returns
to the working state only after a full

More here:

ACPI / Power Management - Architecture and Driver Support"