Hello there, I'd like to report that since kernel 3.15 its nearly impossible to boot past the grub screen because post grub, during X init my monitor starts to endlessly power down/ power on. The only way to boot is to play around with the restart button, in arround 10 restarts, ~once I would get X to initialize properly. The other way is to put radeon.dpm=0 in the kernel-line. This way no errors occur, but I am left without dynamic power managemenent for the GPU.