[eropple]

Can you get them all in the same X session? I've never tried SLI, I generally just upgrade to a beefier main card and use a second card to drive extra monitors. I have an HD6970 and an HD6450 on 4 monitors that work great under OS X (Hackintosh'd) and Windows and things go extremely sideways under Ubuntu.

[dripton]

I had 3 monitors / 2 Nvidia cards working fine in Kubuntu 11.04 and 12.04. All one X session. It was easy. But that was with uniform geometry. (I had 3 identical monitors.) Haven't tried non-uniform.

[rurounijones]

Ah well, Radeon with Crossfire under Linux is... yea, good luck. All I can say is nvidia in SLi works fine.