macosx won't come up


i've tried to install X on my G3/300 minitower with an new 400mhz processor in the socket and an formac performance 3 videocard with 16mb ram. the installation works fine, but after the reboot only a white screen with a repeating message "aty card not supported" (or so) comes up when the miro monitor is on the formac card. when it's connected to the internal video port, the screen stays black. Should i try to boot without the formac card installed? would that help? formac has no X drivers, by the way.

p.s. my linux installation on the same machine works fine with the formac, no driver installation needed.

help would be great.
I think OSX is trying to gently hint to you that your video card is unsupported. unplug it & try again
the videocard is not the problem, it's the internal wideSCSI pci card!! After all a certified apple product!! What should i do? get a new card? buy a IDE drive?