If you get a good clocking Ti or one under water 4k60 is reasonable in nearly everything I have tried with a Ti at 2.1 core 6Ghz RAM with the odd dip, some stuff like BF1 with a 150 res scale needs SLI to keep over 60, SLI is hit an miss, I thought crossfire was better for scaling in my old games ( I had 3x290s ) but it is fair to say that GPUs were not as powerful as 1080Ti so might be why they scaled better, one Ti is similar or better than 2x290s and my scaling could be held back by my Ryzen perhaps? Doubt it looking at where my results place me on the benchmark threads here.
Really you want the 1080Ti under water as in a big gaming session its clocks will drop to ~1.5Ghz. where as water keeps it at 2+Ghz also try and find a higher TDP one, mine throttles not due to heat or voltage now its on water but due TDP.