It's the nature of modern screens, they aren't as flexible as CRT's of days gone by were (I still miss them). They are only designed to run at their native resolution. And it will look awful in anything but native resolution....
Also your eyes will perceive it as terrible too, coming from a glorious 4k image to 1080p is like going from a Bugatti Veyron to a fiat panda.
Don't upgrade from a 3930K, it's immensely powerful and has many years in it yet.
I went from a 3930K X79 to a 5960X X99, and it does absolutely nothing for you in a gaming scenario. Save yourself the money mate, and just buy a more modern GPU like GTX 1070 or GTX 1080
I dunno about that, I think a lot of people myself included are a little nervous at shelling out $1200 a GPU when the GTX 1080 was around for just 2months before this monster came along. I feel a lot of enthusiast are sitting there thinking...."ok what's coming next?"Interesting they have a limit on 2 per customer though. Considering 3-Way and 4-Way has been dismissed for the most part.
I doubt it'll be much faster than the GTX 1080, probably more in line with the difference between 980Ti and Titan X. Virtually nothing in it, regardless of the fact it had more Cuda cores and larger memory buffer.