> replaced it with an ATI-card from my old Peg, but the screen stays grey.

PPC Macs need dedicated (or flashed) graphics cards with PPC-compatible ROM. With MorphOS and Linux this can be circumvented by using an AtomBIOS-based Radeon (R500+) card*.

> I tried another Video-card (I think it is a Voodoo, but I'm not sure, can't find a name on the card).

What happened?


Edit: * While early AtomBIOS versions came already somewhen during R400 series, the MorphOS AtomBIOS parser seems to require the newer AtomBIOS versions that started with the R500 series.

[ Edited by Andreas_Wolf 19.01.2021 - 00:57 ]