Kunra Zether :
Just to correct everyone about gaming on a TV. My 4K TV has 2.0b 4K at 60hrz. It does 4K at 60fps or 1080p at 120fps. Vizio M60-C3 the only thing it doesn't do is croma 4:4:4 but it's 4:2:2 I believe. Alot of people said it would effect the text but it doesn't mine looks beautiful I love it. There are hiccups here and there dealing with 4K like icon size and such but windows let's you adjust all that.
I game on an assortment of monitor types and 4k t.v.'s as well. I'm not aware of a true page to go to for reference but it is known that some manufacturers have similar characteristics as yours. It can be very difficult to track who uses which panels and then which controller boards and then what OS/firmware for TV's. Drivers can also affect how a card sees the t.v. as well as I've experienced(woefully) with the latest ones from NV-I still have to use 378.92 otherwise the newest completely break the features below.
I've got one LG 4k that can do 4:2:2 8bit 4096x2160 60hz and then a HiSense 4k that can do 4:4:4/RGB 8bit or 4:2:2 12bit 4k 60hz and HDR in either. Prior to a firmware update it too could do 4096x2160 60hz and also 1080p 120hz.
My only recommendation for anyone investing in a 4k TV for pc gaming is read a lot of the customer reviews. I mean, really dig through them to see what actual users have experienced. I'm sure you're Visio's 1080p 120hz is a true refresh and not an internal boost on the T.V. It hasn't been uncommon for 4k TV's to have that but people shouldn't necessarily trust the refresh rate printed on the packaging. 1080p TV were notorious for that, they would list 120/240/600 etc but the actual connection was still 60hz. For gaming monitors this info is usually much more easily available as that's part of the marketing strategy.