A pretty annoying issue i had to deal with in GNOME3 on ArchLinux was the screen turning black every 10 minutes while watching a video. Hardware tactics to move the mouse from comfortable movie watching positions needed to be evolved. Like kicking chairs. I finally found the solution on the Fedora Forums.
The solution was to remove gnome-screensaver and install xscreensaver. In xscreensaver I could disable the screensaver.
$ sudo pacman -R gnome-screensaver
$ sudo pacman -S xscreensaver