Unfortunately the statement "But then I realize that most Linux games are not really that demanding" couldn't be further from the truth.

4k gaming is questionable even with Titan xp's on windows to be frank.

Owning both a GTX1080 and now a RX64 there are a few games that pound on these cards even on linux and that's @1440p . A 970 ain't got a cat in hells chance @ 4k. However if you are playing old titles/side scroller's it's not an issue I guess

Regards the real estate for programming , would 2 screens be better if you have room ?

Yes I know there are a few games on Linux that will pound my system even at 1600p, and yes I do have mostly older titles.

As far as real estate goes, from some of the stuff I've been reading and watching(YouTube) a 43" 4K display seems to be better then dual monitors. And at least I get see what all the fuss is about with 4K video and gaming(within limits).

it all depend on what you want to play and what settings you use.
for instance i can play games like bioshock infinite, black mesa, grid, dirt rally and others @4k on my tv at high to max settings. if it's too hard on the gpu you can still use lower (windowed?) resolution or settings.
looking at some benchmarkts it looks like your card should be capable of running most games at 4k with at least medium settings (ok not dawn of war, civ, etc but that's a complete other story ;)).

with your 970's "fake" 4GB Vram you should be interested to keep vram-usage below 3.5gb or it will slow down drastically. that's why this card tends to struggle unproportionally in some 4k benchmarks where it can stand it's ground in other (less vram-demanding) titles (e.g. bioshock or dota vs deus ex)

Off hand I think Mad Max is the most demanding game I have. I took a look over at some of http://phoronix.com/ gaming at 4K articles and Mad Max is some what playable at 4K using the Vulkan API and Tomb Raider really flies even at 4K. Of course something like Deus Ex will be out of the question at 4K even set to low details.

Funnily enough, here I have a 40 inch 4K monitor connected to two PCs - one with GTX 1080ti and the other with a GTX 970. I jumped on the 4K band-wagon over a year ago, and I got quite frustrated with frame-rate on demanding games, so I upgraded to GTX 1080ti to address it. But.... that is only part of the story, you also need a decent CPU (e.g. a recent Core i5 or higher, or Ryzen 5 or higher). As an example, say your game manages 70 FPS on an older CPU, it could be over 100 FPS on a newer CPU, with the same graphics card.

With latest demanding titles, you will have problems running at 4K with a GTX 970. There will be older titles or less demanding titles, which will be okay, but not those demanding ones. I'd expect any isometric style games, you'll be okay with (e.g. Age of Wonders 3). And older 3D games like Serious Sam 3 BFE, depending on whether you can handle it when the frame-rate isn't amazingly high.

I've just given Serious Sam 3 BFE, Shadow Warrior (2013), Grid Autosport, Rocket League, 7 Days To Die, Dying Light Enhanced Edition - a quick play on my GTX 970 machine running at 4K. Apart from Dying Light, they're quite playable. With Dying Light, I could still play at 4K, but my game play was suffering due to the frame-rate.

If you are playing single-player, then you might be fine with 4K and your GTX 970. Playing first person shooters, against your friends - you probably won't be so happy.

Any 2D game, e.g. platformer, arcade game - they'll be fine at 4K. Things like Crypt of the NecroDancer, Rogue Legacy, Dungeon Warfare, Dustforce, Limbo, Darkest Dungeon - no problem.

Then of course, you can always switch down resolution, e.g. to 1920x1080, to play the more demanding titles. That would be my recommendation (unless you upgrade graphics).

Thanks, So most of my games will run at just fine at 4K then. My rig is a i5-4670 w/16GB of RAM and two 1TB SSDs. Well I'm looking at build a building a new rig in a few years anyway.

My most demanding game is X-Plane 11. Run everything up to max and it will bring even the most powerful computer currently on the market to its knees.