This appears to be a software bug in macOS or AMD's drivers. Plugging in an external monitor at certain resolutions (1440p@60Hz in my case) will cause the AMD GPU to draw 18-20W constantly, no matter what it's doing. This causes the total system draw to increase from ~10W to ~30W. All that heat has to go somewhere. If I change the resolution of my external monitor to 1080p the AMD GPU drops to ~4W and the fans are qu…
I’m curious if this is affected by the resolution on the laptop display. I believe the 16” and more recent 15” all default to a slightly scaled resolution, versus the pre-Touch Bar 15” which defaults to the panel’s native 2x resolution.
The fans sit just fine at the minimum speed under this setup, nice and quiet... until I start to do anything even remotely demanding, like, oh, open Ableton Live. Used to be I could run dozens of tracks and plugins with no fan noise. Now I can't even have a blank project open without the fans spinning up to audible levels. So much for recording vocals!