Install ATI drivers for Sabayon (HD5000 and newer ATI cards)

Just follow the command and it will make sense. I hope :) I suggest you to kill X (if you are upgrading) from TTY and follow the rest.

equo update --force
equo remove ati-drivers
echo "blacklist radeon" >> /etc/modprobe.d/blacklist.conf

Edit /etc/default/grub

GRUB_CMDLINE_LINUX="nomodeset" 

Remove the old drivers. Do not worry you will still get the console if something goes wrong.

equo remove  xf86-video-ati

equo remove --configfiles xf86-video-ati

equo remove linux-sabayon

equo remove sabayon-sources

equo remove ati-drivers

equo install =sys-kernel/linux-sabayon-3.13.5

equo install =sys-kernel/sabayon-sources-3.13.5

equo install =x11-drivers/ati-drivers-13.12#3.13.0-sabayon amdcccle

eselect bzimage set kernel-genkernel-x86_64-3.13.0-sabayon

eselect kernel set linux-3.13.0-sabayon

eselect opencl set amd

eselect opengl set ati

For the initial configuration of the drivers

/opt/bin/aticonfig --initial

or to update your already decent xorg.conf if you like it, but are switching to the proprietary drivers: 

/opt/bin/aticonfig --initial --input=/etc/X11/xorg.conf

Then reboot, and open amdcccle for configuration. 

/opt/bin/amdcccle