In the future, when GPUs can handily run 3x30" at max settings (which I doubt they can now), and when I have the $$ to do so, I am going to go 3x30" monitors. So the main thing for me is having a triple monitor mount that if flexible enough to handle multiple sizes- 20-30-20, or 30-30-30 in either portrait or landscape mode.
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Mobo ASUS MAXIMUS IV EXTREME (REV 3.0) Memory CORSAIR XMS3 8GB DDR3 GPU 2 EVGA 680 FTW 4GB CPU Intel Core i7-2600K Sandy Bridge 3.4GHz (3.8GHz) Drives 2 HITACHI Deskstar 3TB 2 Crucial 256 GB SSD Displays 3 HP ZR30w 30" monitors UPS Cyberpower PP2200SW PSU Antec High Current Pro HCP-1200 1200W Case COOLER MASTER CM Storm Trooper Drive LITE-ON Black 12X Blu-ray CPU cooler Noctua 6 Dual Heatpipe Fans COOLER MASTER SickleFlow 120 OS Windows 7 Premium