The R9 series (all the Rx series, in fact) are very new and a suitable driver is not found in the Saucy repo.
AMD's 14.2 Beta may work, but I have seen many posts where people have still had problems. I don't have one of these newer GPUs, so I have not been able to test them personally. Also, bear in mind that it is a beta, not a final release. I can't vouch for its behavior as a beta!
You will have to install that driver manually by doing one of the following, if you haven't yet tried them with 14.2 Beta. If you have tried them, then I can't help.
In either case, make sure you are downloading the desired driver and take care to change the version names in the commands:
1. Create a .deb file as described in the wiki you referenced at "3. Installing upstream drivers directly from AMD's website". I see one error, though. Instead of using
which had been deprecated, use
sudo aticonfig --initial
which is now preferred. I'll try to correct that some day soon for whoever wrote that section of the wiki. It's a relatively new change.
sudo amdconfig --initial
2. Install directly from the .run as described in "3.2. Manually installing Catalyst 13.4, special case for Intel/AMD hybrid graphics" (you can install it this way even if you don't have hybrid graphics and some things have changed in newer versions (lord, I need to update that section of the wiki!).). Also note that for the second method I have specified that you MUST use
if you install this way and later want to uninstall. Also, this method will NOT automatically update the driver through your package manager.
sudo amdconfig --uninstall
Of the two methods, the first is preferable. As I say in the wiki, the second is really not recommended.
Again, though, if you tried these methods specifically with the beta driver it may simply be that the GPU is too new for AMD to have provided the Linux community with a working driver and I'll have to buy one to work out the kinks when one becomes available. (Mrs. QIII sometimes gets grumpy with me when I suggest that I need to do this for the Ubuntu community, though! She thinks I just want new toyz, which I do!)