PPC ATI MACH64 INVALID CONFIG 11.1

Hi, having a problem, with my MAC blue and white, tried to install 11.1.

Screen goes blank,and get an unsupported mode message, ran the install using video=ofonly worked ok, till the autoconfig for sax set it to the mach64 mode. the system goes blank, ended up removing the disk drive, and editing the xorg.conf on an other machine, got it to work with 8 bits in the install config mode, ran sax again, and was rewarded with an invalid mode again…

my system does not look real good in 8 it color at 800X600, can anyone help me solve this problem?

Thanks