This is only a problem, as I have no solution.
I tried to set up my new Vizio M70-E3 display (circa Dec 2017) to accept HDMI audio/video from two Acer Veriton N4640g mini-PCs. These PCs are quite capable and run Windows 7, which I prefer. They are also small and almost silent, and so good media PCs.
The Veriton is VGA only. I figured that I could use a VGA-to-HDMI adapter to convert the signal. However, the adapters I tried did not work.
(For anyone reading who is unfamiliar with Vizio TVs, they have no
discrete audio inputs. If they had, I would have bypassed the HDMI
video first thing. But this is not possible.)
The first was the Cable Matters VGA-to-HDMI Converter with USB Audio. The video on this worked perfectly but there was no audio. The drivers were fine and Windows showed the USB audio device playing, but the TV did not play the audio. I tried several ports, several HDMI cables, and two separate identical converters without success.
Figuring there was an issue with the USB audio, I next tried the Bytecc VGA-to-HDMI with 3.5mm audio. The 3.5mm jack on the PC worked, but the TV again refused to play audio.
Finally, I tried the Vantec USB 3.0 to HDMI 4k converter. I didn't have much hope, but the audio worked perfectly (surprisingly). However, the video playback was ever-so-slightly laggy, making it unsuitable even with locally stored 1080p video files. I don't know if the issue was with the Core i5, the Veriton USB, or USB 3.0 performance in general, but it didn't make it.
In the unlikely event that anyone other than me wants to try this, be aware that the Vizio M70-E3 does not like the audio signal produced by x-to-HDMI converters. Be sure you test the configuration beforehand.
Also, as a note, anyone looking for a "media PC" might want to look at a laptop/notebook instead. They are frequently cheaper than a "media" or "mini PC" when on sale, are just as quiet/power-efficient, have better specs, will fit most media centers (when folded closed) and are (in my experience) much easier to set up owing to the built-in screens and keyboards. I snagged a couple of new Win 7 laptops on sale to fix my issues and they worked very well.