That’s what I saw at first as well so I went into my NVIDIA Control Panel and for some reason the refresh rate was set ot 30Hz … for some reason that’s the default? Luckily I had the 60Hz option for the 3840x2160 resolution.
I think older model TV’s have a 30Hz limit at 4K unfortunately which is ok for watching movies but not ok for computer monitor use. I’m glad you’re liking the 1080p!