My X5000 setup is as follows
16X Slot I have a Radeon Rx 570 that I use for OS 4.1
1X slot with 16x adapter I use a Radeon 1950 with MorphOS
1X slot with 16x adapter I use a Radeon HD 6870 for linux


If I put the Radeon HD6870 instead of the Radeon RX 570 MorphOS works well while if I use it with the 1x-16 adapter it doesn't
but if I use the Radeon 1950 with 1x-16x Mos adapter it works fine
Advice is welcome