@bernd
The Voodoo4 supports most every gfx mode but the big endian modes have problems with the colors of some objects. This is an Elbox bug for a long time and they don't seem too enthusiastic about fixing. Having big endian and small endian modes open at the same time can cause gfx corruption according to Elbox. Elbox recommends using little endian modes. Did your demo open in big endian mode? That would explain why it ran so fast too.