X on IBM pSeries

Hi all, I'm having a hard time trying to get the X server running on my IBM pSeries 640 B80. The machine's using the Matrox G200 SD (IBM: GXT 130), but no matter what I try, I always get the standard resolution of 640x480. I installed SuSE 7.1 (running 2.4.2 POWER3 kernel) from scratch using Yast1 because of the RPM bug of Yast2. Neither sax2 nor xsfbswitch are working for me, and for the Matrox card, there is no kernel option (like for the ATI cards: video=atyfb ...) I tried modifying the XF86Config, but even if the only resolution given is different from 640x480, startx defaults to that. The G200 should run at 1024x768 (with 8 bit depth), since it has 2MB memory. Any hints, suggestions, success stories? Thanks in advance Ferdi