Going to either start building or looking for a streaming PC for only Facebook Live. Only using one 1080p camera at the moment. May add a 4k in the future.

I've been looking at Ryzen 3 and Ryzen 5. Also at Intel i5/i7. Not sure which one would be the one to get. I don't want to get more than I will ever need or not get enough.

As for the GPU I've been looking at the 1050/1060 and Rx series.

Any suggestions on what to use for the Cpu and Gpu? Thanks in advance.

The mentioned reference systems definitely help if you're not a fan of guesswork or anxiety.

I'm a bit of a believer in underdogs, so I went with a Ryzen 3900X paired with a RTX 2060 and Decklink Duo 2. I had to stretch a budget that took a 50% cut, so futureproofing for UltraHD wasn't in the cards. UHD was such low priority though. I originally planned on using a GTX 1660, but I'm glad I went with a RTX 2060. The 2070 was too high of a price jump for me at the time... dropping even to a Ryzen 5 wouldn't have covered the price difference.

My initial aim was to pull of 720p59.94 with 5 encodes, but I've been happily running at 1080p59.94 with 4 encodes.

There's a bit more of an emphasis on GPU versus CPU, but with UltraHD/4K, you definitely can't be a cheapo on either. On the bright side, a 3060 Ti is considered an equal or better performer to the 2080 Ti at a lower price point... provided you can find one not from a scalper. Also make sure you have enough PCI-E lanes to cover everything you want.

What video standard you use is ultimately up to you, but I personally would aim for being able to do 1080p59.94 (or 50 depending on your locale) before taking on the UltraHD/4K resolutions. I think the fluidity of 59.94/50 is more reminiscent of broadcast TV and is more impactful than higher resolution. Whenever the Super Bowl runs in UltraHD, it's been an upconvert from 1080p59.94. But again, it comes down to personal taste.

Whatever you do, give yourself plenty of time to test and tweak. Don't expect things to be perfect the instant you have vMix installed.

Oh boy, don't fall down that rabbit hole.

GPU is very important. Just about everything you do in vMix is GPU driven. Playing a MP4? That's GPU. Streaming and/or recording? GPU also. Yes, you can fall back to software rendering, but you will quickly eat up your CPU. Whether or not you're using NDI is largely irrelevant in this case.

Case and point: my first trial run with vMix was on a Dell Latitude with only Intel onboard video and 2 NDI|HX cameras. I had to drop everything down to 720p29.97 to not be an absolute disaster. Even with that, I dropped a significant amount of frames just doing a single encode. Full NDI would likely have not made a difference. Everything was running at full tilt.

Don't get hung up on the HDMI port part. I use lots of SDI and that's definitely not a free lunch. It's a picture. At some point it needs to be rendered, and that is GPU. The stuff I've stated earlier still stands too.

If you're not convinced, all I can say is make use of the free trial and make sure your system is up to snuff. If you're thinking of using Radeon, understand that vMix is optimized for Nvidia cards, including hardware video encoding. Familiarize yourself with the hardware requirements on the site and all the material they put out to help you get started.

Also give yourself some leeway so that you don't instantly build an antiquated system that can't keep up as your productions evolve.