So I decided to trial clamshell mode for work today, despite being a committed "lid open" user I thought I should try it to see if there was any difference in fan noise. Found a bluetooth keyboard and mouse hidden in a drawer (Logitech K850 keyboard and Logitech M720 Triathlon mouse). No change to my apps usage - MS Office, MS Teams, MS Outlook, Chrome, Safari, Monday, Apple Music.
The difference is pretty stark. Whereas with the lid open the 5500 Radeon was drawing close to 20W power and the fans were spinning up noisily at 5,500rpm+, in clamshell mode the GPU is drawing 5-7W and the fans are spinning at 1,800rpm (silent) for most usage, up to about 12W with fans at 3,000rpm when on a MS Teams call. This is with Turbo Boost enabled. Will try with Turbo Boost disabled later today.
Compromises in this mode:
1) I preferred using the MBP 16 keyboard.
2) I liked using the Touch Bar (there, I said it
). Why? For easy volume control and also I use Touch ID all the time for passwords on Safari. Now I'll have to remember them
3) I liked the integral speakers on the MBP16 for conference calls. They're excellent. The speakers on my Philips 346B1 monitor are distinctly average. So, for now, I'm Airplaying sound to a Apple HomePod on my desk. Will see how that goes. Good sound obviously, as long as the lip sync is OK. So far so good.
So, I reckon I'll accept these compromises in order to have less heat, fan noise and actually be able to participate in MS Teams calls with less of a noise issue. I will still however, continue my escalation with Apple support on the "lid open connected to monitor" noise problem. I see clamshell mode as a workaround only, but for now, it's better.