single desktop with 2 different cards.
Having already one card, planned to add a second card and 2 more screens, but googling while found that should be possible, also found some points that add more confusion to how to setup it properly.
First issue is didn't find any information of how this does affect performance if the two cards are different. Asuming the 3d window isn't spanning multiple cards, is safe to assume that lower performance card (older one) won't affect/slow the newer one?
Second issue is a mix of xinerama and twinview, having read of issues with xinerama vs twinview, would be a good choice first use twinview to join screens on the same card, then xinerama to join both cards?
Also am asuming there should not be problem on setting all screens in horizontal desktop, then the outer screens are of one card, while at centre place of the other card.