DVI-D only carries a digital signal, while DVI-I has digital and analog(so you can use a dvi to vga adapter). Both ports come in single link and dual link versions. Dual link is needed for larger resolutions like 2560x1440 and for higher refresh rates like the 120Hz and 144Hz monitors.
Great, thank you! So you are saying that with the ports available on the single 780 Ti, I should be able to hook up all three monitors at 2560x1440 correct? I can use the Dual Link DVI-I, the DVI-D, and the DisplayPort to hook up a total of 3 on one card?