@Wayne: Normally I use the binary ati driver (x11-drivers/ati-drivers) but also gave the free one (x11-drivers/xf86-video-ati) a try with the same results.
@Wayne: Normally I use the binary ati driver (x11-drivers/ ati-drivers) but also gave the free one (x11-drivers/ xf86-video- ati) a try with the same results.