Install Windows 8 Pro Update without a previous product installed

Some people like me wants to install a fresh installation of Windows 8 without having Windows 7 pre installed. It’s faster and probably cleaner too. The only problem is that the early Windows 8 Pro Keys were Update Keys so they can’t be used for a full installation. After searching at Google I found a way to tell Windows that is was installed through the update process and finally activate my key :

  • Start regedit as administrator (Windows+R key and type regedit)
  • Go to HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE
  • Edit MediaBootInstall from 1 to 0
  • Start a command prompt as administrator
  • Type slmgr /rearm and reboot with shutdown /r
  • After restart, go into the command prompt as administrator again
  • Type slui.exe 3 and enter your key
  • If the last step doesn’t work, reboot and try the last command again.