Looking for input on hardware

If you saw my post a couple of days ago, I am going to give a TLDR of it here first:

My GPU stopped supporting dual display for some reason, and everything I've tried to fix it has not worked. Single display from either port works, but dual display doesn't, and I need it for my work.

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So, with that out of the way, I am looking to get a new GPU to put in my computer. Also, from my previous post, I am always reluctant to upgrade ( I am still on 10.12.2), but I have been thinking about making the upgrade leap recently, but still am queazy about it. I think if I am going to get a new GPU, I might as well start fresh and install all of my stuff fresh and get a newer OS and professional software combo and continue to do updates until I find one that is relatively stable and stick with it for the next few years again. With that said, I have been out of the pc parts game for a while, and am unsure if my current processor and MB combo will run Catalina effectively:

i7 - 6700k

GA Z170-MX

Is it worth upgrading software, or am I looking at an entire new machine basically at this point?

Also, any recommendations on a GPU? My last one was Nvidia, and while I have no qualms about the performance or anything, I recall having to jump through a lot of hoops to get it to work correctly and to give more than just a black screen. Ideally, I would like to purchase something that is a little more "plug and play" and will require less of the headache I went through with Nvidia drivers and such. The only requirement I have is that it runs dual display. I don't need it to be the best thing out there at all. I just need to run 2 displays (hopefully at 1080p).

Thanks for any advice you guys may have!