https://bugs.freedesktop.org/show_bug.cgi?id=64850
--- Comment #30 from George Emigh glemigh@yahoo.com --- Had the same problem with XFX R7750 Core Edition 1G (ATI Cape Verde PRO [Radeon HD 7750])
I applied the patches found in this bug report to 3.11.0-gentoo kernel, they seemed to apply fine and now I have 2 working displays.
Thank you very much.