Alright let's get started. To setup three monitors you'll need a little more than a graphics card alone. You will need a feisty PC with proper rendering horsepower.
So the ingredients for our little experiment are:
X79 / Six Core Core I7 3960X @ 4600 MHz
Radeon R9 295x2
Two NEC MultiSync E231W monitors (FullHD)
One AOC Q2963PM 21:9 (!) 2560x1080 (WFHD)
Three sets of power cables
Three sets of Display Port to Mini-Display port cables
A bit of time
To be able to create an Eyefinity cluster of monitors all you need to do is hook them up to your graphics card. Please do use DisplayPort whenever available. DP is very flexible with Eyefinity, has plenty of signal bandwidth and overall is easier to work with. That's said, obviously you can use DVI and HDMI on your AMD cards just as well.
AMD Eyefinity 3-panel Mixed Resolution review We review AMDs Eyefinity 3-panel with Mixed Resolutions. A new feature added to their Catalyst 14.6 Beta drivers, you can now mix several monitor resolutions and still create an Eyefinity (multi-screen) gaming setup.