I'd love to buy one of the new 4k monitors, but I'm not sure my machine supports it. I have the latest model (2013) 13" Macbook Air. Apple's website lists the following supported resolutions: 1440 by 900 (native), 1280 by 800, 1152 by 720, and 1024 by 640 pixels at 16:10 aspect ratio; 1024 by 768 and 800 by 600 pixels at 4:3 aspect ratio. But I've heard rumors that the 2012 Macbook Air did work with the 4k resolution 3840 x 2160, even though it wasn't listed as a supported resolution. Supposing my model of macbook air doesn't work with a 4k monitor, can I use some sort of external graphics card to drive it?