So you bought the 4K@60Hz as a casual gamer? I kinda understand your experience. I will not even game on such a monitor. First, playing at native resolution of 4K and then cranking down all the details in-game simply defeats the purpose of having a 4K monitor in the first place. Second, playing games (especially fast-paced FPS) capped at 60Hz is a thrust back to the era of Command and Conquer (pun intended). Worse, you may also observe
screen tearing, which happens when your graphics card is rendering frames faster than your monitor can display them. You can of course enable VSync which caps your frame rate to 60fps, but you’ll get a
higher input lag which truly sucks for an FPS. In any case, I will not advise playing fast-paced FPS on a 60Hz monitor, much less at 4K native resolution. And your GTX 980Ti obviously isn't an ideal card for 4K high frame-rate gaming.
It's debatable which is worse: cranking down all in-game details at 4K native resolution OR playing at lower resolution with a far smoother experience and with the highest in-game details.