With that much money you could build two really good gaming PCs. I personally don't think you should pay that much money for a PC (I think it starts to get a little overkill around 1200-1500 US dollars), but it's your money.
The question is what do you want most out of your PC? Do you want to play almost all games on high-max settings at 1080, 1440, 4k? Do you have a specific game in mind? Do you want to overclock? Do you do a lot of CPU/RAM/GPU intensive tasks outside of gaming like 3d rendering/modeling, Video Editing, or working on high resolution images on Photoshop? You have to buy what you think you're going to utilize at it's full potential. Spending 1800 bucks on stuff you don't need would be totally unnecessary. You could use the rest of that money to buy yourself a decent monitor and peripherals for your PC or leave some money aside if your planning on upgrading (like your GPU).
I'm personally not great at picking out more pricier components since I just usually try to make the best budget PC builds. If you really want to keep the 970 then you have to build a pc that can utilize it at it's full potential. Which shouldn't cost 1800 dollars.
I made this for you if you're interested.
pc partpicker com /list/bTbD7h (sorry I can't post links). I assume you want to overclock? I don't think you need SLI support to be honest.
I also made one if you don't want to overclock. pc partpicker com /list/RzyTpb (can't post links). I change the CPU into a Core i5-6500 instead of a 6500k plus it comes with a stock fan! You could change it to a liquid cooler if you want or get a better cpu cooler. I'm keeping the z170 MOBO because although an h170 would be fine on non K intel cpus, I really want to use DDR4-3000 Ram. Plus maybe you'll eventually upgrade to a Intel k CPU.
That leaves you with about 1000 dollars to spare. That should be enough for future upgrades or even buy a decent monitor and/or periphrials. Also an OS too if you like buying Operating Systems. Maybe buy yourself a nicer case!