High CPU Temperatures when plugin external monitors.

16-in 2019 intel MacBook Pro heat and performance:

This computer was built with a ninth generation 14nm Intel processor. The only way to meet the target performance was to make it a six or eight core processor. This processor generates an enormous burst of heat when it does Turbo Boost, and there is only one cooling rail shared by both the CPU and GPU. So getting Either side too hot ramps up the fans.

This processor was supposed to be an eleventh-generation 7nm processor, but intel is three years late, and is only starting to ship its tenth generation 10nm processors now.

The drive in this computer is more than 100 times the typical speed of computers a decade older. It is the "Muscle Car" of notebook computers. If you have installed software that wastes computer resources on a regular basis, such as speeder-uppers, Cleaner-uppers/Removers, Optimizers, Virus Scanners, third-party file Sync-ers such as DropBox, OneDrive, or GoogleDrive, or a VPN that you installed yourself, it will do busywork at previously-impossible speeds — heating up at a ferocious rate.

Apple DID redesign the cooling system for this specific Mac. New, high-efficiency fans are used. But for some uses, that is still not enough.

Some of the best advice is to install Turbo Boost Switcher and turn off CPU Turbo Boost. This reduces the huge sudden overheating brought on by Turbo Boost, that simply does not translate into real-world performance gains.

For external displays, changing away from HDMI to DisplayPort family (or to DisplayPort over ThunderBolt or USB-C) will reduce the Voltages and slightly reduce the heat generated. It is a good thing to do, but it may not be enough to solve this issue by itself.

Welcome GeorgiosGR,

It sounds like you have issues with fans and CPU usage after connecting your two external monitors to your MacBook Pro. We'll certainly do our best to help out.

If you haven't yet, we'd confirm there are no updates or firmware updates for your external monitors. We're not sure which macOS you're using, but if it's up to date, it would be best to ensure the external monitors are, as well.

With that said, we'd also disconnect these monitors from the Mac for at least three minutes, then reconnect them. Then test this further using recovery on the Mac. This boots us outside of the macOS, and will tell us if the issue is software or hardware related. You'd want to shut down the Mac using the Apple menu > Shut down. Then power on the Mac holding the 'R' key on your keyboard until it boots up to recovery mode. Once you get to macOS Utilities, select on Safari and search the web a bit to test the monitors out. You can also shut down from the Apple menu > Shut down in recovery, as well. See more in: Mac startup key combinations - Apple Support

To test the issue even further, try out safe mode: How to use safe mode on your Mac - Apple Support

These steps can help you to isolate the issue and depending on the results, how to handle the solution.

How to use safe mode

Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:

Apple silicon

1. Shut down your Mac.

2. Turn on your Mac and continue to press and hold the power button until you see the startup options window.

3. Select your startup disk, then press and hold the Shift key while clicking “Continue in Safe Mode.”

4. Log in to your Mac. You might be asked to log in again.

Intel processor

1. Turn on or restart your Mac, then immediately press and hold the Shift key as your Mac starts up.

2. Release the key when you see the login window, then log in to your Mac. 

3. You might be asked to log in again. On either the first or second login window, you should see ”Safe Boot” in the upper-right corner of the window.

If the issue continues in safe mode

If the issue continues while in safe mode, or your Mac restarts several times and then shuts down while starting up in safe mode, you should reinstall macOS and make sure that your Apple software and third-party apps are up to date.

If the issue doesn't continue in safe mode

If the issue doesn't continue while in safe mode, leave safe mode by restarting your Mac normally. Then test for the issue again. The issue might be resolved.

If the issue returns after leaving safe mode, startup items are probably at fault. Apps can install such items in numerous places, and they aren't always easy to find or recognize. For that reason, you should first make sure that you've installed any available updates for your Apple software and third-party apps.

If updating your software doesn't help, try any of these solutions:

- Test your login items.

- To learn whether software in your user account is causing the issue, set up a new user account, then log in to it and try to reproduce the issue in that account.

- Unplug all accessories from your Mac, including printers, drives, USB hubs, and other nonessential devices. You could have an issue with one or more of those devices or their cables.

- Reinstall macOS.

If you still need help, please contact Apple Support.

Lastly, this covers how to keep your Mac within acceptable temperatures since the Mac runs warmer than expected: Keep your Mac notebook within acceptable operating temperatures - Apple Support

If the issue persists, what macOS version are you using? Any firmware updates for the monitors? What were the results of safe mode and recovery? As these answers will help us to narrow things down even further.

Hoping to hear how it goes, take care.