Caporegime
Ive gone for an ROG swift gsync monitor. 75c is on the stock fan profile but i used the same one i had with my old sli 780 setup. 65c max with it and very little noise. Tbh ive used this card very little for gaming, recently switched from a Z87 system to X99. No games currently installed as my back up hdd kicked the bucket mid build. Card is in the top slot of my msi mpower board.It will be hotter but not much 4K is the real strain its a massive jump over 6m pixels more than 1080 hence the sudden heat/noise.
I think a single GTX 980 Ti will be fine @ 1440. 4K though really needs as Kaapstad said SLI under water as a minimum for decent FPS.
Surprised your getting 75C @ 1200 though mine is only 65-67C @ 1080 in most games. I do have a 120mm side case fan sucking cool air directly over the backplate & a 2" gap all round now as I moved the card to the 2nd PCI-E slot so its on its own.