This is long but recaps what I’ve done and Apple has done to date. The good news is that with the aggressive fan settings that I setup in iStat Menus, I can work ok with a single external display or with just the built-in display. I haven’t tried video editing yet with Final Cut Pro that I recently purchased. I’m going to try going through some of the video tutorials on how to use it, and see how that that goes.
It’s really easy to recreate the issue. all I have to do is have 1 external display attached and open the built-in display. The Radeon GPU power draw will shoot up to 20W , and the system will overheat and reboot after about 10 minutes.
— T/S Log
Macbook Pro Troubleshooting Log
Problem: 16" Macbook Pro gets excessively hot when using external display.
Details: Macbook Pro temperature exceeds 65C when one or more external displays are connected. Fans speed up to 3000rpm and higher. I can’t hear music , video calls, or anything else over the fans, so it’s work stoppage at that point. If I ignore the fans and continue working, eventually the Macbook Pro will freeze ( trackpad and keyboard stop responding) for a moment, and then reboot itself. The last CPU PECI temperature reading I get before reboot is 70C.
4/19/2020 Troubleshooting Session 1
Investigation
I did testing with my 16" 2019 Macbook Pro 2.4Ghz i9/radeon 4gb/32gb ram, using the below hardware
Turbo Boost was disabled. GPU autoswitch enabled.
Hardware
Dell U2718Q display.
Dell P2715Q display connected with Displayport to mini Display port and Monoprice mini DP to USB-C adapter.
The display doesn’t have USB-C, so I cycled Displayport and HDMI using adapters.
Monoprice Mini Displayport -> USB-C Adapter
No-name Displayport -> USB-C cable ( straight cable , no adapter in between )
Apple HDMI -> usb-c adapter
Results
The idle temperature with no external display is ~41C Fan 1800rpm.
The idle temperature with DP->USBC connected external display is ~60C 3000rpm
The idle temperature with HDMI->USBC connected external display is ~61C 3000rpm
Solution : None.
Some interesting observations
Apple recommends putting external displays on separate usb-c busses. So plug on in on the left and one the right side of the laptop.
Adding a 2nd external display ( Dell P2715Q ) Bumped the temperature up to ~65C , I didn’t record the fan.
With no external display, built-in was using Intel UHD GPU. with 1+ external displays, all displays ( no just external) were using Radeon GPU.
I’ve gotten the fans and temp under somewhat under control with iStat Menus and Turbo Boost Switcher Pro.
After 5-6 hours of testing and research with every combination of monitor, cable, adapter, and connection configuration and display settings configuration that you could think of, I’ve concluded that there isn’t a solution using the hardware and software that I currently own.
Someone asked about applications. It’s always the same applications using the most CPU. Generally Windows Server and whichever app I playing video with. Browser apps like Slack or Chrome will generally be right next to Window Server when I am using them for video calls or (Chrome ) playing video content like Youtube videos. The same goes for any media player, aka VLC, that I might be using. I also tested with video conferencing applications such as Webex and MS Teams. They all cause my Macbook Pro’s temperature to go into orbit. Basically, anything that plays video will turn my Macbook Pro into a pizza oven.
4/19/2020 Troubleshooting Session 2
I should have mentioned that I switched iStat Menus versions from the App Store to the vendor Website version. The app store version is watered down and doesn’t have fan control or power monitoring.
With the new power monitoring ability, I can see power draw for the Radeon GPU,
- no external displays ~0w.
- 1 external display ~6W
- 2 external displays ~20W
I tested each display by itself, together, connected through dock , connected directly to the Macbook Pro, connected on the same side, connected on different sides - the power draw seems to only care about how many displays are connected.
Btw, this is idle with no videos playing or other GPU intensive app running.GPU Usage is 0% per activity monitor.
4/20/2020 Troubleshooting Session 1
I did some more testing with the power meter. The GPU went to ~20W under 3 different conditions with my 2019 Macbook Pro 16":
- 1 External Display and Built-in Display active
- 2 External Displays active
- 1 External Display active and Chrome playing youtube videos or (strangely enough ) just opening https://www.apple.com/logic-pro/ . Safari did not have this issue. It stayed at ~6w GPU power draw.
My employer’s laptop is a 2017 Macbook Pro w/Radeon Pro 555 and Intel HD 630 GPU’s. I haven’t repeated all of the tests but here is what I have so far.
- 1 External Display and Built-in Display active ~9W ( less than half of 2019 Macbook Pro!)
- 1 External Displays active ~6W - same was 2019 Macbook Pro
- 1 External Display active and Chrome playing youtube videos or opening https://www.apple.com/logic-pro/ . ~5W - 25% of what my 2019 Macbook Pro does.
So the older , much less powerful 2017 Macbook Pro draws much less power while connected to the same monitor doing the same things as the 2019 Macbook Pro.
I think this supports with either an issue with my specific 2019 Macbook Pro 16", or a general issue with device. I don’t know which because I don’t have another 2019 Macbook Pro 16" to test with.
Just to clarify - the tests were done buy unplugging one laptop from my Caldigit Dock , plugging the other one in, and using the same OS/Browser/Software to perform tests. And I got very different GPU power draw results.
4/21/2020 Troubleshooting Session 1
Hardware:
I swapped out the P2715Q monitor with another display to see if anything changed. The U2718Q remained the same.
- Dell U2415 display connected with Displayport to mini Display port and Monoprice mini DP to USB-C adapter.
- I connected both Displays to the Caldigit TS3 + dock.
I made a few last ditch efforts to isolate the cause of the issue before contacting Apple Tech Support
- SMC Reset - No change in the issue.
- Safe boot - No change in the issue.
- Clean install of MacOS. I booted into recovery mode, delete the APFS volumes, recreated the volumes, and installed MacOS Catalina. I didn’t perform data restore or migration, and I didn’t log into iCloud. - No change in the issue.
4/21/2020 Troubleshooting Session 2
With both displays plugged into the dock and the problem returned ( 20W GPU draw ). I captured system information using the Capture application as directed by Apple tech support.
No change in the issue.
4/24/2020 Apple Update
I called Apple and they didn’t have an update. I got in touch with another 2-3rd level tech, did a quick review of what I had done so far.
I recreated the heating issue by having 1 external display and the built-in display open. Radeon High Side ~20W and temperate went from 60C to 70C in about 8 minutes.
He opened a follow up ticket to see if any progress had been made with my original ticket.
4/25/2020 Troubleshooting Session 1
I reset NVRAM/PRAM.
Tests
1 External and Built-in monitor. No CPU/GPU intensive apps running. Radeon High End ~18W
1 External Display. Radeon High End ~5.41W
I removed desktop spaces. Going from my normal 6 down 1
Tests
1 External and Built-in monitor. No CPU/GPU intensive apps running. Radeon High End ~18W
1 External Display. Radeon High End ~5.41W
Summary of the hardware used during all of the above testing.
Monitors
- Dell U2415 display. Firmware not available. connected with Displayport to mini DisplayPort cable, and a Monoprice mini DP to USB-C adapter.
- Dell U2718Q display. Firmware not available. connected with Itanda Displayport to USB-C adapter.
- Dell P2715Q display. Firmware not available. connected with DisplayPort to mini Display port cable, and a Monoprice mini DP to USB-C adapter.
Docks
- CalDigit TS3 Plus Dock. Firmware v44.1
Macbooks
- 2017 Macbook Pro 15". Intel I7 2.8GHz, Radeon Pro 555 2GB, 16GB RAM, 500GB SSD, macOS 10.15.4
- 2019 Macbook Pro 16" i9,Radeon Pro 5500M 4GB, 32GB RAM, 1TB SSD, macOS 10.15.4
Cables
- Dell supplied DisplayPort -> DisplayPort Cable
- Dell supplied DisplayPort -> Mini DisplayPort Cable
- Itanda DisplayPort -> USB-C cable ( straight cable , no adapter in between )
- Dell supplied HDMI -> HDMI Cable ( used in earlier tests with HDMI that I didn’t document. )
Adapters
- Apple HDMI/Power/USB -> usb-c 3-in-1 Adapter
- Monoprice Mini DisplayPort -> USB-C Adapter