I'm looking into getting a third monitor for Christmas and I was wondering if I would need any extra cables or connectors to make a triple monitor setup work. I don't want to use all three of my monitors for gaming, I would just use the new one for gaming and have my old ones be for internet browsing, streams, etc.
HDMI versions prior to 1.4 do not deliver sufficient bandwidth for 144Hz 1080p, and many displays aren't properly programmed to allow the pixel clocks above 165MHz needed for displays above 1920x1200@60Hz.
You'll need either Displayport, Dual link DVI-D, or to hack the drivers to get it working properly IIRC. And you're probably using both DVI ports for you existing screens.