https://pcpartpicker.com/product/c298TW/asus-monitor-mg279q
BTW, that's a FREESYNC monitor which is cheaper than GSYNC but requires an AMD graphics card like the RX-480. I do like asynchronous mode for smoother gaming, so I'd recommend that instead of a cheaper, 60Hz panel with more expensive graphics card.
(it's amazing because you don't have to deal with VSYNC ON vs OFF pros and cons like screen tear etc. Just choose the best FPS between about 40FPS and 120FPS average depending on the type of game, visual settings etc and it is really smooth most of the time).
Asus Strix RX-580 8GB card is about $260:
https://pcpartpicker.com/product/9ZmxFT/asus-radeon-rx-580-8gb-rog-strix-video-card-rog-strix-rx580-o8g-gaming
example benchmark:
http://www.guru3d.com/articles_pages/asus_radeon_rx_580_strix_review,24.html
IMO, again, the RX-580 + 144Hz Freesync monitor is better than a GTX1070 and any non-GSYNC monitor.
Huh?
Here's just one example of why. Let's assume a GAME has bad screen tear, and that you have a normal 144Hz (non-Freesync) panel. Well, you don't want normal VSYNC (stutter if you can't hit 144FPS in the game), so Adaptive HALF VSync is the best option. So mostly synch to 72FPS (can apply this to a normal 60Hz as well).
But, to stay at mostly solid 60/72FPS your GPU must be capable of averaging higher. Say, closer to 90FPS. However, with no FPS/VSync issue in Freesync you could run the same game at 50FPS or whatever.
Point is you can have a similar or BETTER experience with a weaker GPU if you also have Freesync (for AMD). I'm talking 144Hz as there are some crappy Freesync panels with a very low range of operation (some only 40FPS to 60FPS).
*Many games are a huge HASSLE to optimize. Some have severe judder/stutter if you can't match VSYNC so trying to balance the game quality (settings) can be a hassle and likely you need to re-tweak some of these games later when things get more demanding. You don't really worry much about that with Freesync or GSync beyond aiming for the best FPS average (i.e. maybe 100FPS for faster games... 50FPS for slower, or just set ULTRA and if the FPS is high enough you're done. eezy peezy.)