Try a fresh boot and don't run any apps. It should idle around ~650RPM
View attachment 334592
The problem is the fan should be OFF when the GPU is not being used for any heavy loads and macOS fails to control it properly.
Under Windows my Vega FE fan is off during idle. (last time I checked)
The thermal curve for these officially supported GPUs are too aggressive and I assume Apple doesn't have time to finely tune proper support, even if they have for example the Vega FE on their eGPU official support list.
I suggest everyone who has a Vega send feedback to Apple and complain about the fan and since it's officially supported, they should fix it. Just mention that you have an eGPU and a supported card from
this list.
https://www.apple.com/feedback/
[email protected]
[email protected]