"Assuming you mean using all three monitors as a single viewport, it looks like you can't just plug 3 screens into 3 DVI outputs -- you need Windows to see the multiple monitors as a single large monitor, either by hardware or software means.
And it appears that you have rather limited options...
Hardware: Matrox TripleHead2Go. Seems to support latest games but only up to 5040x1050 (3x1680x1050). You plug your graphics card output (supports SLI/Crossfire) into one end of the unit and three monitors into the other. http://www.matrox.com/graphics/surroundgaming/en/home/
Software: SoftTH. Does much the same thing in software, supports any resolution but only uses a single graphics card (although you need an extra 'dummy' one to provide the third output). Seems to support only a few older games, might require tweaking."
"Unless you're running something like Flight Simulator X, you should know that most games will not want to span monitors, and those that do will not do it at those resolutions, likely due to the capabilities reported to Direct X from the GPUs. However, you could ""multi-box"" Eve-Online or other MMOs with about 2 windows per screen if you run each eve application under a different windows user account, and rotate the screens.
Just don't get carried away (max cap: 36, shown: ~28):
Also just read the Ars System Guide. Either SLI up the HotRod with a second graphics card and drop the parts you already have (well under $2000), or carefully trim the GodBox to a manageable $2000 budget, if possible. I managed to get the GodBox to under $5000 by dropping the 2nd CPU, Monitors, SAS and all the drives but one. If you follow the single CPU gaming advice there you'd save even more."
