I guess ATI graphics card owners are a bit unlucky! When Fedora 11 was released, we didn’t get the proprietary drivers from AMD for months and the older version didn’t work with default kernel at that time. When Fedora 12 was released, AMD released newer version of Drivers after a few hours. But this time, Xorg becomes a stumbling block and again the driver installation fails for a lot of people!
But Fedora 12 tries to make life a bit easier and may provide support for ATI cards. From Fedora 12 Announcement
Fedora 12 introduces experimental 3D support for AMD Radeon HD 2400 and later graphics cards. To try it out, install the mesa-dri-drivers-experimental package. On many cards, this support should allow desktop effects to be used.
What to do?
Step 1 : Try ATI Catalyst Drivers from AMD
Nobody, so far, has reported the successful installation of ATI Catalyst drivers on Fedora 12. But still if you want to give it a shot (because the uninstall is clean and doesn’t leave a trace of ATI drivers in your system), you can follow How To: Install ATI Catalyst (fglrx) Drivers. If it doesn’t work, just uninstall using the command given at the end of the post.
Step 2 : Try mesa-dri-drivers
Keep in mind that these are experimental drivers and may not work properly or may work partially.
Install the mesa-dri-drivers-experimental from Fedora repositories using Yum.
[root@fedora ~]# yum install mesa-dri-drivers-experimental
Reboot if the drivers are install successfully.
Let me know, if any of the above drivers work for you