Simplified summary of PCI-e slot usage
(hope I got it correct)



A - ATI
N - nVidia
X - miXed

Max. video card modes
1 card - x16
2 cards - x16 x16
3 cards - x16 x16 x16
4 cards - x16 x16 x8 x8
With 3 or 4 video cards installed, slot 3 can still support another card in x1 mode.