@h9826790 - sorry, one more stupid question:
I just looked at my MP3,1 with a Radeon 7950 in it running Catalina. The fans on that graphics card are constantly running - even at idle. Based on what you wrote before, I'm assuming that since the 7950 is an older card, its BIOS is set in such a way that the fans will run constantly and only ramp up under load. Whereas, the Vega 64 being a newer card, has its BIOS telling it that it should only turn its fan on after it reaches a certain temperature threshold.
Is my understanding correct?
The reason I ask (and also why I said this is a stupid question), but my newest GPU is a GTX 1080Ti installed in a Windows box. My experience with newer-ish graphics cards ends with that, and the 1080Ti's fans run constantly irrespective of load. All other previous GPUs I've owned have had cooling fans that constantly spun at idle like the 1080. The Vega 64 is the first card I've owned that didn't do that.
Just want to make sure nothing's amiss with my setup.