Originally Posted by nvidia.com
In 2D Surround, any combination of monitors that share common timings is perfectly acceptable, though each must have, at minimum, one DVI, HDMI, or DisplayPort connector. Aesthetically, identical monitors are preferable, but not a requirement.
In 3D Vision Surround, each monitor must be an identical make and model, and you must use three matching digital connectors. We will go into detail below, but you may need additional adapters for this.
The Accessory Display, the forth monitor, does not have to be identical to the three Surround displays, but does require one of the three possible connectors.
In 3D Vision Surround, any monitor connected to the DisplayPort output must use a DisplayPort to Dual-Link DVI adapter so that all three monitors are using Dual-Link DVI.