.ugo@6tron:~$ sudo aticonfig --tv-geometry=800x600
failed to set tv geometry. 
check help for possible causes. 
Warning: Option 'TVHPosAdj' doesn't affect running session.
Warning: Option 'TVVPosAdj' doesn't affect running session.
Warning: Option 'TVHSizeAdj' doesn't affect running session.
Warning: Option 'TVVSizeAdj' doesn't affect running session.
Using /etc/X11/xorg.conf
Saved back-up to /etc/X11/xorg.conf.fglrx-9