guidox / PC
Run **powercfg /a** to see the available sleep states and why others are unavailable, then check **powercfg /devicequery wake_armed** for devices that can wake the machine.
**powercfg /a** prints each state with a reason when it is unavailable. Standby S3 and modern standby S0 are mutually exclusive, which explains most surprises.
powercfg /a
powercfg /availablesleepstates
Get-CimInstance Win32_ComputerSystem | Select-Object Model,PCSystemType
Get-CimInstance Win32_BIOS | Select-Object SMBIOSBIOSVersion,ReleaseDateThe active scheme decides the sleep timeouts. A scheme set to never sleep looks like a machine that cannot sleep.
powercfg /getactivescheme
powercfg /query SCHEME_CURRENT SUB_SLEEP
powercfg /q SCHEME_CURRENT SUB_SLEEP STANDBYIDLE**wake_armed** lists the devices allowed to wake it; **lastwake** names the one that did. A network adapter or a mouse is the usual culprit for a PC that starts at night.
powercfg /devicequery wake_armed
powercfg /lastwake
powercfg /devicequery wake_from_any
Get-CimInstance Win32_PnPEntity | Where-Object Name -match 'Mouse|Keyboard|Ethernet|Wi-Fi' | Select-Object Name,StatusA scheduled task with a wake flag starts the machine without any device input. Disabling wake timers per scheme is the direct fix.
powercfg /waketimers
powercfg /setacvalueindex SCHEME_CURRENT SUB_SLEEP RTCWAKE 0
powercfg /setdcvalueindex SCHEME_CURRENT SUB_SLEEP RTCWAKE 0
powercfg /setactive SCHEME_CURRENT
Get-ScheduledTask | Where-Object Settings -match 'Wake' | Select-Object TaskName,StateSuspend and measure. The event log records the transition and the wake source, which is evidence rather than a guess from the clock.
Get-WinEvent -LogName System -MaxEvents 200 | Where-Object Id -in 42,107,1 | Select-Object TimeCreated,Id,ProviderName -First 8
rundll32.exe powrprof.dll,SetSuspendState 0,1,0
Get-WinEvent -LogLevel Information -LogName System -MaxEvents 20 | Where-Object Id -eq 1 | Select-Object TimeCreated,Message -First 2**powercfg /hibernate on** creates hiberfil.sys and makes the hibernation state available. It also enables fast startup, which changes how shutdown behaves.
powercfg /hibernate on
powercfg /a
Get-Item C:\hiberfil.sys -Force -ErrorAction SilentlyContinue | Select-Object Name,Length
Get-ItemProperty 'HKLM:\SYSTEM\CurrentControlSet\Control\Power' | Select-Object HiberFileSizePercent,HibernateEnabledThe firmware is set to modern standby, which is a firmware choice. Some boards expose a legacy sleep option in the setup.
A device is armed to wake it. Use powercfg /lastwake, then disable wake on that device with powercfg /devicedisablewake.
Hibernation is off, or fast startup was disabled. Enable it with powercfg /hibernate on and restart Explorer.
A virtual machine platform or a sandbox holds the platform awake. Disable the optional feature if you need S3.
It drains while the lid is closed because the machine is not fully off. S3 uses less power but resumes slower.
It writes the memory content once per hibernate. On a modern SSD that is not a practical concern.
It only exists on machines that support S3 together with hibernation. On S0 systems the option does not apply.
Turn hibernation off again with powercfg /hibernate off if you enabled it only for the test, and restore wake timers with powercfg /setacvalueindex SCHEME_CURRENT SUB_SLEEP RTCWAKE 1.
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