Long story short: in Fedora 20 (and as far as I remember also 19 and 18) XScreenSaver doesn’t power off the monitor backlight when locking the screen. Being the lazy ass I am it took like me 2 or 3 years to find the motivation to solve the issue. It was actually pretty simple, no need to edit some obscure config file or else, in XFCE just click on: Application menu -> Settings -> Screensaver. …