My Macbook overheats insanely.

After investigating a bit, I found out that the correlation is extremely strong with having it plugged in to an external monitor with the Macbook Pro monitor also active.

If I unplug the laptop, or use only the external monitor (i.e. Mac in a 'clamshell' mode), the heating stops within a minute.

I managed to use a software (sudo powermetrics --samplers smc |grep -i "CPU die temperature") to measure this:

  • Indoor temperature: 23C
  • CPU heat without external monitor: 55C
  • CPU heat with external monitor + macbook monitor on: 95C (fan turns on)
  • CPU heat with external monitor, macbook closed: 62C

Details of hardware

  • Macbook Pro (16-inch, 2019). 2.3 Ghz 8-Core Intel Core i9, 16 GB 2667 MHz DDR, AMD Radeon Pro 5500M 4GB, Intel UHD Graphics 630 1536 MB
  • macOS BigSur 11.4
  • Monitor: HP E233. 23-inch (1920 x 1080)
  • Cables connecting: UGREEN USB C Hub HDMI USB C Adapter with 4K HDMI, 3 USB 3.0, SD/TF Card Reader (https://www.amazon.de/gp/product/B07RRPS5NT/), and then a standard HDMI-cable

Tried fixes that didn't work

  • Restart
  • SMC reset
  • Never use two monitors (works)

How could I fix this so I can use two monitors also in the future?

  • Is your monitor plugged in on the right or left?
    – X_841
    Jul 15 at 6:56
  • Left. Dont tell me that this makes the difference :-D
    – ppt
    Jul 15 at 7:15
  • 1
    apple.stackexchange.com/questions/363337/… it may actually be the problem.
    – X_841
    Jul 15 at 9:00
  • That trick used to fix the issue in previous versions (I had a 15" 2016 where it worked), but not anymore. I've tried both sides and now it doesn't. I have an i7 and an i9 (both late 2019) and the issue only affects the i9.
    – t3b4n
    Sep 5 at 3:03

Try this:

  1. Update to latest macos Monterey
  2. Go to Settings -> Battery => Check the Low power mode both for Battery and Power adapter
  3. On using two 4k monitors, if possible use ports on left/right foreach monitor

Good Luck!

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