I am building a computer very soon and one problem is that I don't know if I should go with 3 monitors, 2, or 1. I am using 2 nvidia GeForce gtx 680s o sli. I would be playing games like mw3 or bf3 and minecraft etc. If you need the specs of the build tell me.
You can run a game with three monitors just fine, though for extremely intensive games, you'll have to turn down the graphics.
With two monitors the game is run on one, and you have a second for internet / system monitoring. This is most useful if you play a lot of MMOs, as you can have a much smaller second screen for information.
With one monitor, you can get a good 24" 1080p 120MHz monitor that'll look good and last you forever. This is what I prefer.
I would go with 2 monitors and have one for browsing. But if you have three monitors, that means that you are basically running the game three times. Metro 2033, which I think is probably the hardest game to run, gets 48 fps 680 sli in 1920x1200 resolution at highest settings. So that is really the only game you would need to turn down settings for. BF3 would get about 50 I'd guess, it gets 130 with one monitor. But I think it might be best to get just 2 monitors, and if you do get two, I would recommend getting a cheaper one for your second monitor.