Advice on adding HDMI 2.0/4k to an aging (but capable) HTPC

So I built an HTPC quite a while ago, and while it has served me VERY well over the last 8 years or so, I just upgraded my main living room TV to a new LG OLED 4k TV (E6P), and I’ve come to the realization that my motherboard’s HDMI output isn’t rated for 4k (not sure if it is 1.4 or not, but I’ve had the board since 2008, so I know it isn’t 2.0).

What I’d like to do is add a low profile video card that does support HDMI 2.0 & 4k playback, but a challenge that I am seeing is that my motherboard (GIGABYTE GA-E7AUM-DS2H) is quite old only supports PCIE 2.0 in the x16 slot, where the new card I’m looking to get (GTX 1050 2GT LP) is PCIE 3.0 in the x16 slot. I shouldn’t have a problem running the 3.0 card in the 2.0 slot.

However, my question comes in as is this worth it? I’d like to be able to play as much content as possible on this box (currently, I can play everything I throw at it with either hardware decoding via the embedded geforce 9400 gpu, or the C2D E8400), so I’m not sure whether I should stick with LibreElec (which I’ve read can’t do 10bit HEVC), or move back to Windows 10 (which can do everything).

I have a new Yamaha receiver that is capable of decoding Dolby TrueHD & DTS-HD, so I’d like to take advantage of that as well. I currently have an Nvidia Sheild as a temporary stop gap, but want to know if it is worth it to upgrade the video card on my HTPC, just keep using the Shield, or get different hardware entirely?

I have read through the stickied thread, and based on that, it looks like I’m down to either the Shield or a LibreELEC box, but I’d like to know if I can just add the GTX 1050 to my current HTCP and use that, rather than building a new box (on either Windows or LibreELEC).

Thanks!