If use the xrandr command and set a wrong resolution/freq/..., can a break my display devices?For instance, by setting a very high refresh freq that one of the video devices involved (video card, monitor, ...) does not support.
Can I break display devices with the xrandr command?
xorg;xrandr
In the early 90's there was indeed the danger of breaking CRT displays when setting too high frequency, but I don't think this is still a big problem. Modern CRTs should just refuse to work with unsupported frequencies. Still with any CRT there is some danger, at least this is what wikipedia says... Wrong resolution doesn't do any harm.