[Rebelgecko]

Even though opening the lid makes the GPU work harder, it typically is a win in terms of cooling the laptop down. Also, try plugging in the power adapter on the right side USB ports, that allegedly makes a difference in heat

[biztos]

The reason I started running it in clamshell mode, after years of keeping my 13" open, was the the GPU would massively overheat when running an external monitor, so I'd have the fans running at well over 50% all the time in that case. Clamshell fixed it at the time.

Seems to play nicer with my other (Dell) monitor but when I was using Garage Band (only on the external monitor!) it got so loud I had to quit GB and let it cool down... and I still never went over about 20% CPU. The fans are pretty normal when I only use the built-in monitor, but the case still gets way too hot to rest on my legs.

I'll try the right side power, thanks for the tip!

[dotandgtfo]

My 15 inch mbp 2019 got super hot when I ran the dock (with HDMI and keyboard) on the same side as the charger. Having them on opposite sides helped loads with the temperature. YMMV

[biztos]

Whoa... this seems to have done it. (I think.)

Thanks a lot for the tip! Funny, that's how I had it connected with the previous monitor and I didn't have trouble with the clamshell mode.

FWIW right-side power didn't help, nor did the turbo switcher AFAICT (I'm not doing anything CPU-intensive) -- but as soon as I put the monitor in the left and the power in the right the fans dropped way down. Still running, which is annoying, but not especially loud.

I find it maddening that a $3600 computer has a problem like this, and Apple doesn't even tell you about it.