16" Macbook Pro gets excessively hot when using external display

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 a stops my work at that point.

Investigation

I did testing with my 16" 2019 Macbook Pro 2.4Ghz i9/radeon 4gb/32gb ram, using

Dell U2718Q display. Turbo Boost was disabled. GPU autoswitch enabled.

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.

Questions :

  • Would using an USB-C external display with native support help? ie a display the does not require an adapter.
  • Would using an eGPU to drive external displays help? If the heat issue is due to the internal Radeon GPU, then I would think offloading to an external GPU would fix it. Expensive, but an option.
  • How do view power draw? I have iStats but don’t see power usage mention anywhere.This is important as some have theorized that the real issue is that certain models of displays draw too much power, leading to the temperature to increase.

Update:


Update 2
I’m looking into using iStats Menus fan control in addition to disabling Turbo Boost.

Hm. Are the fans really that loud? Wow.

My 2015 15.4" MBP is usually running pretty hot with an external display. I don’t think I’ve seen it go below 60°C since I first plugged this in. I worry about long-term damage to the Mac, but the fans aren’t disruptive to me in the way you describe, so I just live with it.

(I keep the MacBook itself closed at my desk.)

Doesn’t this hinder the air flow path from the MBP?

I’d consider using an external USB powered cooling pad as well. I got one of these (in white) a few decades ago at a surplus store. It has served me very well to this day.

https://www.amazon.com/Belkin-CoolSpot-USB-Powered-Cooling-F5L055btBLK/dp/B00GLBI2IY

I also use a stand like the one below for my home setup.

https://www.amazon.com/AmazonBasics-Portable-Adjustable-Aluminum-Fans-Silver/dp/B07KYR2DKC/ref=sr_1_27?dchild=1&keywords=cooling+pad&qid=1587251546&sr=8-27

I’ve noticed that it does help pull down the temperature perhaps a few degrees when I’m running hot.


JJW

2 Likes

I’m sure you’re right, though I haven’t noticed a substantial difference between now and when I used the MBP display as a secondary display. Perhaps running the laptop display offset any cooling gains from better airflow.

I do have mine elevated a little, but I haven’t considered a powered fan stand. Thanks!

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I use my MBP16 with an UltraFine 5K all day long at work and while it runs slightly warmer when plugged in, I wouldn’t call it “hot” and I don’t hear any fan noise.

Unless there is a hardware issue (e.g. mainboard, bad sensor), fan noise is almost always directly related to a process (application, system utility, etc.) that is really pushing the CPU and/or GPU. CPU is pretty much all processing except graphics, while GPU is graphical display processing. The processors generate heat when they are pushed really hard and the system responds by cranking up the fans to get rid of the danger.

Try the tests again with Activity Monitor open and sorted descending by % CPU. (click on the % CPU column header so it shows a down-arrow):

As you plug in monitors, see if there’s any process that jump up in the top five or so spots. If you don’t see any changes, try sorting by the % GPU column and repeating your test.

If you see a process that is consistently jumping to the top of the list when sorted by CPU or GPU, that may indicate that application or system process is incompatible with a specific external display or needs an update. If its an app you can shut down, quit it and see if the high CPU/GPU returns when you repeat testing.

Good luck and keep us updated!

5 Likes

Remember to power the fans from a separate powered USB source, not from the computer itself.


JJW

2 Likes

I don’t have any solution for you, but I have a 16" MBP that’s driving two 4K displays through a single connection to a Belkin Thunderbolt 3 dock. One display is a Dell and the other is an Asus and both are running in (scaled) 4K resolutions, though I do leave the lid on the MBP open (better cooling and 3rd display). I don’t have the problem that you’re describing, so it’s not something inherent to running external displays on that model.

One thing worth noting is that once you connect external display to a Macbook Pro with a discrete GPU, it will use that GPU for everything.

1 Like

I’ve gotten the fans and temp 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. 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.

Solutions that might exist but I can’t test because I don’t possess the hardware or Apple has to create a fix or because they don’t fit my requirements.

  1. eGPU - offload the driving of external displays to an external card.
  2. Native USB-C Display - None of my displays have USB-C ports, so I have to use adapters to connect them to my Macbook Pro. The adapters may be increasing power draw and therefore also increase heat. A native USB-C display would remove that as a possible issue.
  3. Don’t use external displays. For this, I’d need to change my workflows from dual 27" to fit a single 16" display. For posture and vision( I wear glasses ) reasons, I’d need a stand to hold the Macbook Pro up to the correct eye level and distance from my eyes. This would definitely solve the heating issue as I tested it. The Macbook Pro stays at 41C no matter what applications I’m running when using only the built-in display.
  4. Radeon Driver Update - On macrumors.com forums, people smarter than me analyzed the Radeon drivers and settings and they believe the issue is with the driver, which Apple has not updated (according to file date ) since Catalina’s initial release. A drive update may fix the issue. I can share the thread here, it’s about 45 pages of posts, so it isn’t a quick read. :slight_smile:
  5. This one is out there. A few people suggested using third party utilities to change the refresh rate from default 30Hz to 60Hz. I noted that for my displays, Catalina doesn’t expose refresh rates when using the option + scaled method of view display configurations. So I would need a 3rd party tool such as SwitchResX.

For my use case, either the Catalina driver update or the purchase of USB-C displays would be the easiest. My workspace setup is shared between my Macbook Pro and my employer’s Macbook Pro since I’m working from home these days.

Right now all my peripherals either connect to my CalDigit dock( which I bypassed during testing ) or my Display’s USB port. To switch Macbook Pro’s , I swap the dock’s usb-c cable from one Macbook Pro to the other. Easy peasy!

This isn’t likely. The problem is creating and moving all the bits to support the displays, not the amount of power the display uses (or the adapters).

This will likely make things worse, as your laptop will have to supply twice as much information.

2 Likes

With everything said and done, I am not sure that I understand whether these reports really show where the problem is. I cannot believe that an external dock would not compensate for the required power draw. Bypassing it would in my mind only enhance the problem not diminish it.

  • Connect one monitor and nothing else to the dock or MBP. What happens at full on work load?
  • Repeat with the other monitor.
  • Repeat with both monitors.
  • Now add back other peripherals one at a time.

When you find that one or the other components causes a heat overload, try running with that component directly connected to the MBP (bypassing the dock).


JJW

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 test 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.

I suspect it is the GPU producing a lot of the heat. I had the same issue when using a 4K external monitor and second 1080p one. Adding an eGPU stopped the fans from spinning up completely, now it is silent even under load.

2 Likes

I did some more testing with the power meter. The GPU went to ~20W under 3 different conditions the the 2019 Macbook Pro 16":

  1. 1 External Display and Built-in Display active
  2. 2 External Displays active
  3. 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.

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. 1 External Display and Built-in Display active ~9W ( less than half of 2019 Macbook Pro!)
  2. 1 External Displays active ~6W - same was 2019 Macbook Pro
  3. 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.

1 Like

I just received a refurbished 16" yesterday from Apple. First thing I noticed was the fan turned on and is running far more than the 13.3" I replaced. I thought it was just because I was transferring, etc. but this morning the fan turned on immediately upon booting up. I’ve run CleanmyMac X and it’s still doing it all 8 cores are running at 151º or higher. Does this seem unusual?

My MBP 16" also getting hot very quickly when I attach external 4k display. Previous 15" wasn’t behaving like that. At first I thought that the issue with my Satechi HDMI adapter-hub, because it’s also get’s hot or because of sun shining from the window and heating my mac, so I’ve ordered a cooling pad (not received yet) and thinking about using different adapter or cable. But from this discussion I understand that it’s more global. I’ve installed the iStat Menus and see that when I attach the display it switches to GPU, but also takes all the memory of the GPU (98%-99%) and keep using it. So I think it’s probably an issue with driver @majorgear mentioned. As I understand the only thing we can do is to wait for the Apple to update drivers?

Based on what I’ve been reading, that seems to be the only fix. When I brought it home and connected to an older HDMI monitor (720p) the fan never came on for 20-25 minutes. I’m going to try scaling down the resolution on my other monitor and see if that helps.

Just today I was having a read and saw that in some cases using the thunderbolt ports on the left side of a MacBook Pro will potentially cause heat related throttling.

1 Like

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
1 Like

I suspect that you are right. The overheating seems to follow the stat “Radeon High End” . When that goes above ~10W, the CPU PECI temp starts climbing faster than the fans can cool it off. It looks like the fans can handle 6-7W, but somewhere about that it crosses a point of no return.

It’s not total power draw. If the Radeon < 10W but my power draw is high for CPU usage or charging the battery, like a system total 55W, the temperature doesn’t go out of control. Only when the GPU pulls too much power does the system overheat.

1 Like

It really sounds as if there’s something wrong with your system. I’m not seeing anything like that and I use external displays all the time. I really hope that you can get it sorted, because it sounds like you have a hardware issue :frowning: