https://bugs.freedesktop.org/show_bug.cgi?id=93826
--- Comment #17 from Alex Deucher alexdeucher@gmail.com --- The pll divider combination that is getting selected doesn't seem to agree with that monitor. You can try adjusting the algorithm in radeon_compute_pll_avivo() or the pll flags passed to radeon_compute_pll_avivo() in atombios_adjust_pll().