What variations of sleep does my computer support? And why did it wake up?


POWERCFG has the answer to that question and many others, like -LASTWAKE will tell you why your machine resumed form sleep or hibernate.  I used to run into an issue where I’d wake up in the morning and find my laptop was at perfect temperature to cook an egg, used -LASTWAKE to find out why…

C:\Windows\system32>powercfg -AVAILABLESLEEPSTATES
The following sleep states are available on this system: Standby ( S3 ) Hibernate Hybrid Sleep
The following sleep states are not available on this system:
Standby (S1)
The system firmware does not support this standby state.
Standby (S2)
The system firmware does not support this standby state.

C:\Windows\system32>powercfg -LASTWAKE
Wake History Count – 1
Wake History [0]
Wake Source Count – 0


The LASTWAKE info I supplied above wasn’t too helpful.  LASTWAKE is dependent on your hardware and drivers and not all support this functionality yet and so you’ll get either reports where it is too general (USBHUB) or nothing at all as you see above.

Here is what it looks like when your hardware and drivers support this functionality.  Tracking what woke the system is new for Vista, so it’s going to take some time for firmware, hardware and drivers to catch up.

 C:\Debuggers>powercfg -LASTWAKE
Wake History Count – 1
Wake History [0]
  Wake Source Count – 1
  Wake Source [0]
    Type: Device
    Instance Path: ACPI\PNP0C0C\2&daba3ff&1
    Friendly Name:
    Description: ACPI Power Button
    Manufacturer: (Standard system devices)

Comments (8)

  1. Anonymous says:

    There is a tonne of information available on Vista power management, from whitepapers to videos to blog

  2. BooRadely says:

    It depends on your hardware at this time, I’ll update this post with the new info.

  3. BooRadely says:

    Think it’s only for Vista.

  4. David Moisan says:

    Not that "Wake History[0]" is really descriptive.  How did you use that information to determine why your laptop was waking?

  5. Wizou says:

    Do you know a way to access the same information as powercfg -lastwake on XP SP2 whose powercfg doesn’t seem to have this feature ?

  6. Alex Skorkin says:

    Thanks for giving use of LASTWAKE and other information… Sacatech

  7. Computer Support Kingston says:

    give the microsoft support site a try

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