Sometimes your computer wakes for no apparent reason, want to know why?
From a command prompt run powercfg -lastwake
Powercfg is a very useful tool, below is a list of switches :-
POWERCFG <command line options>
Description:
This command line tool enables users to control the power settings
on a system.
Parameter List:
-LIST, -L Lists all power schemes in the current user’s environment.
Usage: POWERCFG -LIST
-QUERY, -Q Displays the contents of the specified power scheme.
Usage: POWERCFG -QUERY <SCHEME_GUID> <SUB_GUID>
<SCHEME_GUID> (optional) Specifies the GUID of the power scheme
to display, can be obtained by using powercfg -l.
<SUB_GUID> (optional) Specifies the GUID of the subgroup
to display. Requires a SCHEME_GUID to be provided.
If neither SCHEME_GUID or SUB_GUID are provided, the settings
of the current user’s active power scheme are displayed.
If SUB_GUID is not specified, all settings in the specified
power scheme are displayed.
-CHANGE, -X Modifies a setting value in the current power scheme.
Usage: POWERCFG -X <SETTING> <VALUE>
<SETTING> Specifies one of the following options:
-monitor-timeout-ac <minutes>
-monitor-timeout-dc <minutes>
-disk-timeout-ac <minutes>
-disk-timeout-dc <minutes>
-standby-timeout-ac <minutes>
-standby-timeout-dc <minutes>
-hibernate-timeout-ac <minutes>
-hibernate-timeout-dc <minutes>
Example:
POWERCFG -Change -monitor-timeout-ac 5
This would set the monitor idle timeout value to 5 minutes
when on AC power.
-CHANGENAME Modifies the name of a power scheme and optionally it’s
description.
Usage: POWERCFG -CHANGENAME <GUID> <name> <scheme description>
If the description is omitted only the name will be changed.
-DUPLICATESCHEME
Duplicates the specified power scheme. The resulting
GUID which represents the new scheme will be displayed.
Usage: POWERCFG -DUPLICATESCHEME <GUID> <destination GUID>
<GUID> Specifies a scheme GUID obtained by using the powercfg -l.
If <destination GUID> is omitted, a new GUID will be
created for the duplicated scheme.
-DELETE, -D Deletes the power scheme with the specified GUID.
Usage: POWERCFG -DELETE <GUID>
<GUID> obtained by using the LIST parameter.
-DELETESETTING
Deletes a power setting.
Usage: POWERCFG -DELETESETTING <SUB_GUID> <SETTING_GUID>
<SUB_GUID> Specifies the subgroup GUID.
<SETTING_GUID> Specifies the power setting guid.
-SETACTIVE, -S
Makes the specified power scheme active on the system.
Usage: POWERCFG -SETACTIVE <SCHEME_GUID>
<SCHEME_GUID> Specifies the scheme guid.
-GETACTIVESCHEME
Retrieve the currently active power scheme.
Usage: POWERCFG -GETACTIVESCHEME
-SETACVALUEINDEX
Sets a value associated with a specified power setting
while the system is powered by AC power.
Usage: POWERCFG -SETACVALUEINDEX <SCHEME_GUID> <SUB_GUID>
<SETTING_GUID> <SettingIndex>
<SCHEME_GUID> Specifies a power scheme GUID and may be
obtained by using PowerCfg /L.
<SUB_GUID> Specifies a subgroup of power setting GUID and may
be obtained by using “PowerCfg /Q.”
<SETTING_GUID> Specifies an individual power setting GUID and may
be obtained by using “PowerCfg /Q”.
<SettingIndex> Specifies which of the list of of possible values
this power setting will be set to.
Example:
POWERCFG -SetAcValueIndex <GUID> <GUID> <GUID> 5
This would set the power setting’s AC value to the 5th entry
in the list of possible values for this power setting.
-SETDCVALUEINDEX
Sets a value associated with a specified power setting
while the system is powered by DC power.
Usage: POWERCFG -SETDCVALUEINDEX <SCHEME_GUID> <SUB_GUID>
<SETTING_GUID> <SettingIndex>
<SCHEME_GUID> Specifies a power scheme GUID and may be
obtained by using PowerCfg /L.
<SUB_GUID> Specifies a subgroup of power setting GUID and may
be obtained by using “PowerCfg /Q.”
<SETTING_GUID> Specifies an individual power setting GUID and may
be obtained by using “PowerCfg /Q”.
<SettingIndex> Specifies which of the list of possible values
this setting will be set to.
Example:
POWERCFG -SetDcValueIndex <GUID> <GUID> <GUID> 5
This would set the power setting’s DC value to the 5th entry
in the list of possible values for this power setting.
-HIBERNATE, -H
Enables-Disables the hibernate feature. Hibernate timeout is not
supported on all systems.
Usage: POWERCFG -H <ON|OFF>
POWERCFG -H -Size <PercentSize>
-Size Specifies the desired hiberfile size in percentage of the
total memory. The default size cannot be smaller than 50.
This switch will also enable the hiberfile automatically.
-AVAILABLESLEEPSTATES, -A
Reports the sleep states available on the system
Attempts to report reasons why sleep states are unavailable.
-DEVICEQUERY
Return a list of devices that meet the specified criteria.
Usage: POWERCFG -DEVICEQUERY <queryflags>
<queryflags> Secifies one of the following criteria:
wake_from_S1_supported Return all devices that support waking the
system from a light sleep state.
wake_from_S2_supported Return all devices that support waking the
system from a deeper sleep state.
wake_from_S3_supported Return all devices that support waking the
system from the deepest sleep state.
wake_from_any Return all devices that support waking the
system from any sleep state.
S1_supported List devices supporting light sleep.
S2_supported List devices supporting deeper sleep.
S3_supported List devices supporting deepest sleep.
S4_supported List devices supporting hibernation.
wake_programmable List devices that are user-configurable
to wake the system from a sleep state.
wake_armed List devices that are currently configured
to wake the system from any sleep state.
all_devices Return all devices present in the system.
all_devices_verbose Return verbose list of devices.
Example:
POWERCFG -DEVICEQUERY wake_armed
-DEVICEENABLEWAKE
Enable the device to wake the system from a sleep state.
Usage: POWERCFG -DEVICEENABLEWAKE <devicename>
<devicename> Specifies a device retrieved using
“PowerCfg -DEVICEQUERY wake_programmable”.
Example:
POWERCFG -DEVICEENABLEWAKE
“Microsoft USB IntelliMouse Explorer”
-DEVICEDISABLEWAKE <devicename> disable the device from waking the system
Disable the device from waking the system from a sleep state
Usage: POWERCFG -DEVICEDISABLEWAKE
<devicename> Specifies a device retrieved using
“PowerCfg -DEVICEQUERY wake_armed”.
-IMPORT Imports all power settings from the specified file.
Usage: POWERCFG -IMPORT <filename> <GUID>
<filename> Specify a fully-qualified path to a file generated by
using “PowerCfg -EXPORT parameter”.
<GUID> (optional) The settings are loaded into a power scheme
represented by this GUID. If not supplied, powercfg
will generate and use a new GUID
Example:
POWERCFG -IMPORT c:\scheme.pow
-EXPORT Exports power scheme, represented by the specified GUID, to the
specified file.
Usage: POWERCFG -EXPORT <filename> <GUID>
<filename> Specify a fully-qualified path to a destination file.
<GUID> specifies a power scheme GUID and may be obtained by
using “PowerCfg /L”
Example:
POWERCFG -EXPORT c:\scheme.pow
381b4222-f694-41f0-9685-ff5bb260df2e
-LASTWAKE Reports information about what woke the system from the last
sleep transition
-HELP, -? Displays information on command-line parameters.
-ALIASES Displays all aliases and their corresponding GUIDs.
The user may use these aliases in place of any GUID on
the commandline.
-SETSECURITYDESCRIPTOR
Sets a security descriptor associated with a specified
power setting, power scheme, or action.
Usage: POWERCFG -SETSECURITYDESCRIPTOR <GUID|ACTION> <SDDL>
<GUID> Specifies a power scheme or a power setting GUID.
<ACTION> Can be one of the following strings:
ActionSetActive, ActionCreate, ActionDefault
<SDDL> Specifies a valid security descriptor string in SDDL
format. Call POWERCFG -GETSECURITYDESCRIPTOR to see
an example SDDL STRING.
-GETSECURITYDESCRIPTOR
Gets a security descriptor associated with a specified
power setting, power scheme, or action.
Usage: POWERCFG -GETSECURITYDESCRIPTOR <GUID|ACTION>
<GUID> Specifies a power scheme or a power setting GUID.
<ACTION> Can be one of the following strings:
ActionSetActive, ActionCreate, ActionDefault
-REQUESTS
Enumerate application and driver Power Requests. Power
Requests prevent the computer from automatically powering off
the display or entering a low-power sleep mode.
-REQUESTSOVERRIDE
Sets a Power Request override for a particular Process, Service,
or Driver. If no parameters are specified, this command displays
the current list of Power Request Overrides.
Usage: POWERCFG -REQUESTSOVERRIDE <CALLER_TYPE> <NAME> <REQUEST>
<CALLER_TYPE> Specifies one of the following caller type:
PROCESS, SERVICE, DRIVER. This is obtained by
calling the POWERCFG -REQUESTS command.
<NAME> Specifies the caller name. This is the name
returned from calling POWERCFG -REQUESTS command.
<REQUEST> Specifies one or more of the following Power
Request Types: Display, System, Awaymode.
Example:
POWERCFG -REQUESTSOVERRIDE PROCESS wmplayer.exe Display System
-ENERGY
Analyze the system for common energy-efficiency and battery life
problems. The ENERGY command should be used when the computer is
idle and with no open programs or documents. The ENERGY command
will generate an HTML report file in the current path. The ENERGY
command supports the following optional parameters:
Usage: POWERCFG -ENERGY [-OUTPUT <FILENAME>] [-XML]
[-DURATION <SECONDS>]
POWERCFG -ENERGY -TRACE [-D <FILEPATH>]
[-DURATION <SECONDS>]
-OUTPUT <FILENAME> – Specify the path and filename to store the
energy report HTML file.
-XML – Format the report file as XML.
-TRACE – Record system behavior and do not perform
analysis. Trace files will be generated in
the current path unless the -D parameter
is specified.
-D <FILEPATH> – Specify the directory to store trace data.
May only be used with the -TRACE parameter.
-DURATION <SECONDS> – Specify the number of seconds to observe
system behavior. Default is 60 seconds.
-WAKETIMERS
Enumerate the active wake timers. If enabled, the expiration of a
wake timer wakes the system from sleep and hibernate states.