Here is my specific experience. I have an nVidia GTX 560 Ti card and was running Black Ops II at around 110 FPS. I bought a new 27" 2560X1440 monitor and set the game to native resolution. As expected my FPS dropped to 75 to 80. Then I hooked up my old monitor (1920X1200) as secondary monitor. Now when I run the game, the second monitor goes black but I only get around 20 FPS in game. As a test, I disconnected the second monitor and I was back to 75 FPS. I used to have two monitors before, but it never affected my gaming. I think the new monitor which requires dual link DVI to run at native resolution, has some adverse affect on my video card. If anyone knows why this is, please let me know.