Does it help when you change it? (Maybe that's the only solution for now..)
I don't know your hardware but maybe there is a bug already in bugzilla ( https://bugzilla.redhat.com/
), or you could file a new one.
Assuming you hava a NVIDIA card, you could try to disable nouveau and use the NVIDIA drivers or the old nv drivers and see if that helps.
For nv: add "nouveau.modeset=0 rdblacklist=nouveau" in your kernel options in grub.conf and change your xorg.conf by changing nouveau into nv. Note: the nv drivers have no 3d support .
For NVIDIA: install the rpmfusion repository and run "yum install kmod-nvidia" or "yum install akmod-nvidia".