I've heard from the fbdev list that matroxfb in recent development kernels has code which initializes some functions on those cards to make up for holes in BIOS initialization. Also that it supports multihead on G400, or at least, that's one of the goals. And of course 64-bit cleanliness is a goal...
I'm not an expert on any of this, but if you haven't tried using the framebuffer, it might be worth a try- just to boot up with fbs on both cards, then run X 4, and see if it makes a difference. Zeen, -Adam P.
