https://bugs.freedesktop.org/show_bug.cgi?id=66942
--- Comment #5 from Alex Deucher agd5f@yahoo.com --- Sounds like you may be waiting for the firmware loader to timeout. Make sure you have the new cayman smc ucode installed: http://people.freedesktop.org/~agd5f/radeon_ucode/CAYMAN_smc.bin