Many of the computers we sell here at Puget Systems will be used for playing games, and we also get a lot of folks wanting to run two (or more) monitors. Sometimes those goals intersect, and in those situations I have had people ask if they needed to get a second video card so that using additional monitors will not impact their performance for gaming. I myself use two monitors here at work, which has been a great improvement in usability, but I don't play games in the office. Because of that I've had to fall back on anecdotal evidence when this topic comes up, and make educated guesses depending on individual scenarios. Rather than continue in that approach, though, I wanted to get hard numbers to support my advice.
This plainly shows that adding a second monitor - even if you are doing fairly standard sorts of work on it - has almost no impact on performance of a game. Going so far as to run a second game of course is a major impact, and I could tell on the game I was playing that it wasn't nearly as smooth as it would have been without the benchmark running at the same time. Short of that, though, it looks like you can run two screens off one video card without needing to worry about losing performance in a game!
Tags: Computer, Gaming, Dual Monitors