I decided to buy this last night. Seems good so far, but runs pretty poorly for me. Not sure why, because my system isn't all that bad; 980ti, AMD 8350,16gb ram. 1080p drops down to 25fps occasionally.
Somethings up there...I have a 1070, so roughly equal (I think) to your card.
I run it @ 1440p (downsampled) and it's not even breaking a sweat.
Do you run any monitoring s/w to see if you have any bottlenecks?