Referring to http://en.opensuse.org/ATI/Troublesh...#ATI_AGP_Cards
Here it is stated "If fglrx is still not working, set the AGP aperture Size in the BIOS to the size of the physical card memory."
I know this is not the AGP mode but the aperture size.
Also i recall from the very early days of the nvidia linuxdriver ('t was in the riva tnt time) that AGP modes had considerable effect on driverperformance.
@ Bridgman, i will get back to you later in the proprietary drivers section on hickups witg catalyst 9.6 in sabayonlinux.