GTX 1080 works well enough with a Freesync monitor. The only issue I have is that my monitor has only the basic Freesync, so I'm missing some features.Good data to know in a brief bit of reading. I recently bought a Freesync monitor and have been wanting to pair it with an 6800 XT, but that looks like it probably won't happen for a year now so I'll be sticking with my GTX 1080.
I just wish that since HDMI 2.1 cables have the capability of 4K HDR @ 120 Hz, support could find its way to HDMI.
My next monitor (in 2-3 years) will have at least the Premium version, preferably Premium Pro. By that time the prices will be even better, if the world does not turn upside down until then... which is a real possibility nowadays.