https://bugs.freedesktop.org/show_bug.cgi?id=69341
--- Comment #21 from langkamp@tomblog.de --- did you tried a recent git version? you also could try the oibaf ppa with (k)ubuntus - you wrote you tested only plain kubuntu. Maybe you also have to set radeon.dpm=1 in grub. I have not tested without it.
in the end it could also be a opensuse thing (but i don´t believe that) or a hardware fault (I have an gibabyte OC version)
my best guess at the moment is radeon.dpm=1