I've been struggling all night to get my three Dell u2711 work in EyeFinity.
First I tried three Displayport -> DP-min cables.
All three worked in extended desktop, but not in Eyefinity.
Reason: Must connect all monitors to the same graphics card.
Then I tried one Displayport -> DP-mini and 2x DVI.
Two monitors got 2560x1440 allright, but one couldn't go above 1600x1200. For Infinity to work all monitors had to be set to the lowest common resolution.
Reason: The lower DVI output on the graphics card is not Dual Link, it is only Single Link!
Third setup was the charm! 2x Displayport -> DP-mini cables and one Dual Link DVI (in the top output).
Windows Desktop had no problems running 2560x1440 (or the reverse in portrait) on all three monitors.
It took a while to configure Eyefinity. I kept getting a problem where Eyefinity created the group, but when accepting the config I only got three mirrored (cloned) desktops in 1440x2560.
Solution: First set the extended desktop as you want it with the correct resolutions. Then enter Catalyst and enter
Desktop Properties (translation may not be correct, my Catalyst is in Swedish). There you will see the layout and also have one black triangle in the upper corner on each monitor. Here you can add them to an EyeFinity group and from there on you should find the correct steps in a normal EyeFinity configuration with the blue screen selection etc.
This is Star Wars: The Old Republic in 4320x2560:
And Battlefield 3 in 2700x1600:
CrossFire seems to be working fine, since I run pretty high settings in both games.
I will try some with Skyrim after the holiday.
Merry Christmas to you all!