update:
You said "ULTRA" so just FYI you can't play all games at Ultra, 1440p, 60FPS even with a GTX1080 (and good CPU etc).
So you'll still need to tweak some games. (do NOT just crank to Ultra and accept whatever resolution you get. Set an FPS goal. Maybe force "Adaptive VSYNC" for a game "NCP-> manage 3D settings-> add game..."
Then tweak settings so you drop below 60FPS maybe 5% of the time. That's a great balance of visuals whilst avoiding screen tear. If you use VSYNC OFF then aim for at least 40FPS average.
It sounds like you should keep the GTX1070 though since you want the highest quality.