Thanks for the explanation--best I've seen. I checked the temps in Ryzen Master tonight. It is giving the same temperature readings as I was getting with CPUID HWMonitor.
I was correct in my assumption... the CPU fan profile was set to "Standard" in the BIOS. I set it to "Maximum" and re-ran the trans-coding test. The peak temperature dropped to 62C with the fan running at 2077 RPM. I set it back to "Standard" and re-ran the test so I could see what speed the fan is running since I failed to record that earlier. Set to "standard," the fan peaked at 1849 RPM while achieving a peak CPU temperature of 70C.
I found this article on ITX coolers for Ryzen. My results with the NH-D9L jive with the results presented in the article when the author tests with AIDI64 FPU. I guess I'll go ahead and test with the Cryorig C7 when the AM4 adapter arrives since that is my only option of coolers I currently have that will fit in the MI-6, but I don't expect it to be sufficient.
My next step will be to fork over $60 when I can afford it to get the NH-L12. Either that, or just run this system in my NCASE M1. But, I prefer the CCD MI-6.
In that case, if the reading in Ryzen master is 70C, then you have plenty more headroom, at least 20C.