timf79 :
There is a no doubt the 1080 TI will be faster, but the question is how much?
As in worth to spend the price difference between selling used 970's to a mew 1080 TI?
As in worth to spend the price difference between selling used 970's to a mew 1080 TI?
From my understanding, SLI gtx 970 is not very far from a single 980ti on average, so you have quite a good comparison there.
using the 980 as a reference point
970 SLI was 145% as fast (100 / 69) as a 980 at 2560 x 1600
https://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_970_SLI/20.html
1080 Ti is 212% (100 / 47) as fast as a 980 at 256 x 1440
https://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_1080_Ti/30.html
The 980 Ti was only 120% as fast (100/80) as a 980
https://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_980_Ti/31.html
In summary ....
1080 Ti - 212
970 SLI - 145
980 Ti - 125