Couple of things to note:
Check to make sure the card is even capable of outputting that resolution
Buy a card that has a hardware video decoder for what you're going to watch. That will be loads better than having the GPU, or worse, the CPU brute force it. YouTube uses the VP9 codec, which you can find what has hardware decoding support at https://en.wikipedia.org/wiki/VP9#Hardware_implementations
Because the title is bugging me, I hope you're not thinking of using a VGA connector here.
On that note, the ezpz answer here would be a GT 1030, RX 460, or RX 550.
Taichi Ultimate doesn't have BIOS flashback, so you'd have to update the BIOS with an older CPU first before it will recognize a 3rd gen CPU. It's not as good for running a ton of memory fast either (3733+) compared to the X570 Taichi.
As for other options... what makes you look at the Taichi series in the first place?
sappheon reacted to Mira Yurizaki in VGA out GPU for 4k monitor
