For 4K, no single graphics card will be able to max out games right now. I'd look at dual graphics card systems at least for 4K. The R9 295X2 is an interesting option for this, since it shouldn't cost much more than a 980 and offer much better performance (although I'm not familiar with its european prices). Other than that, you could consider dual 970's as well, or dual 980's, but the 980's cost a lot more for not as much more performance.