Windows wakes up the PC at seemingly random times

Find out which timers are active: 

powercfg /waketimers

Update Task Scheduler

  1. Download PSExec
  2. psexec.exe -i -s %windir%\system32\mmc.exe /s taskschd.msc
  3. Task Scheduler Library → Microsoft → Windows → UpdateOrchestrator.
  4. Right click the task called Reboot
  5. click on Disable.

Connected Standby

  1. regedit
  2. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power
  3. CsEnabled → 0