High GPU Power Consumption While Using External Monitor in MacBook Pro 16-inch

Under heavy loads, the fans will make noise, and that is as expected. These MacBook Pro have Amazing capabilities never seen before in a notebook format.

Several work-arounds have been proposed that tend to reduce fan activity under MODEST uses:

• using DisplayPort family interfaces (or Thunderbolt or USB-C) as opposed to heartbeat-refresh interfaces such as HDMI or DVI or Analog VGA, especially at higher than 60Hz refresh rates.

• Closed clamshell mode, which turns off the built-in display, a heartbeat-refresh display.

• disable Turbo Boost with a third-party Utility.

• applying the power adapter through the RIGHT side instead of the left.

As always, "your mileage may vary".

I just got my 16 inch MacBook Pro and have the same issue.

This is my setup:

MacBook Pro (16 inch, 2019)

2,4 GHz 8-Core Intel Core i9

32 GB 2667 MHz DDR4

AMD Radeon Pro 5500M 4 GB

Intel UHD Graphics 630 1536 MB

with

Kensington TB3 Dock

with

LG 32 inch 4k display via Display Port

My tests results match what others where saying:

The MacBook 16 inch is staying cool when I use it only with internal monitor, or if I use my external 4k monitor with MacBook in Clamshell mode (display closed).

The graphics card is struggling, if I use both an external 4k monitor and the MacBook’s internal monitor and use high resolutions, e.g. 3360 x 1890 (HiDPI)

When I choose 3360 x 1890 in low DPI for the external display, the graphics card relaxes and the system cools down.

Even with HiDPI resolution the load of the system isn’t high and it’s only at around 65°C, but the fans still go crazy at around 4000 - 5000 rpm.

To summarize: The performance is very nice, but the fans go crazy when the graphics card needs to power an external 4k monitor together with the internal monitor.

I reported it to Apple and will report it to AMD, too.

I can confirm that my MacBook Pro 16" connected via either an LG 4k 27" or the LG 5K2K 34", has the following behaviour:

• clam-shell mode: fans at about 1700-1900 RPM, as normal, low noise
• lid open (it does not matter if display brightness on MBP is zero, or if mirror displays or extend desktop mode): fans about 3200-3300 RPM, noisy

So yeah, I don't mind the clam-shell mode but we loose the True Tone on the external monitor in this way, which is a pity.

I have the same problem, my second Mac. This appears to be a software bug in macOS or AMD's drivers. Plugging in an external monitor at certain resolutions will cause the AMD GPU to draw 18-20W constantly, no matter what it's doing. This causes the total system draw to increase from ~10W to ~30W. 

My specs:

2.3 GHz 8-Core Intel Core i9

16 GB 2667 MHz DDR4

Intel UHD Graphics 630 1536 MB

1 TB Flash Storage

We may need a new thread simply titled - $$$ MBP16 degrades performance and longevity due to needlessly high GPU power consumption and see if it gets any attention. :(

There's a huge thread over on macrumors (search 16" IS HOT AND NOISY) but beyond the fans and noise, it's also likely we'll see reduced battery and possibly other component life, at least for those routinely exercising their CPUs and/or GPU.

One comment that has me more concerned than I've been to date is someone working with multiple MBP 16s and starting to see longevity issues across his company's stock - this is concerning if true as even if they were day 1 adopters, that's only 6 months in.

The majority of my MacBooks have been MBPs with dGPUs, and I still have one of the 'problem Nvidea MBPs' still running, but this is concerning. Especially when even the iGPU can handle external screens and the AMD5500 does not see this power draw effectively 'at idle' on other platforms(both OS and hardware).

I am less concerned about power consumption rising when under active loads for either GPU or CPU, as that's the purpose of power levels, throttling etc., but a baseline GPU consumption of ~20W from as clean boot, doing nothing - is simply adding needless heat into the system as a new overly hot all-the-time baseline, and when combined with <active but not always-on loads> still has a net effect of more heat into the system, which is never a good thing.

Someone mentioned some 150+ page thread over here - anyone have link to it?

I did file the issue with AMD as well. I haven't gotten a response as of yet, but someone else stated they did, with AMD saying they simply provide the chip and Apple owns the driver and implementation.

Link to the much bigger thread which was started back in November, and has at least one IT guy trying to work through the issues on multiple work systems with Apple.

https://discussions.apple.com/thread/250878229?page=1

wegster wrote:

We may need a new thread simply titled - $$$ MBP16 degrades performance and longevity due to needlessly high GPU power consumption and see if it gets any attention. :(

Doing that here won't do any good. This is an end user forum and the handful of Apple Mods are so busy keeping the wheels on this massive forum that they do not have time to read and report threads to Engineering. I've been here almost 20 years--trust me on this.

The best action has already been posted: the feedback link. That gets information to Apple employees working in development and things get done. This is the link for MacBook Pro issues:

Feedback - MacBook Pro - Apple

I've been fighting this since Thanksgiving weekend, same issue, power consumption goes up over 19W when the lid is open and connected to an external monitor.

Since some on these forums had success with reducing the power load through going with a monitor that can accommodate higher refresh rates, I bought a new monitor with 1440P/144 Hz capabilities. Connected to my MBP 16 with the lid open (via USB-C cable to DP 1.2), I get the same result; 19.5W.

Tried several different refresh rates and resolutions, same result.

I only have one monitor plugged in other than the internal screen - I am likely going to have to run in clamshell mode until they fix it. No Touch ID, no Touch Bar, none of the features that makes it a MacBook Pro.

I am reporting to Apple again today.

I have little doubt the feedback link will do wonders either, but filed nonetheless. :)

I work in tech and have worked for some Apple competitors at times, and know how huge support forums go.

I doubt the general feedback link has much of a chance vs some Apple employee (not necessarily moderators) seeing a thread blowing up in here and perhaps taking internal action, but either way, feedback filed, and will re-file next time I'm open to a beta again vs work craziness.

For anyone following along, I'd <do all of the above> - report in if you have an issue, but also follow the feedback link Grant provided and fill it in as well. If you guys are on dev or public beta, file it there as well. Eventually perhaps it will be seen by one of the right people.

Temps etc. for my above post as we seemingly can't edit once posted.. :-/

MBP 16 32 GB RAM, 2TB SSD, 8 GB AMD.

Single external 38" UQ QHD+ 3840x1600 attached. Makes no difference in cable attachments, with or without dock, 18W+ minimum. Wanted to add a second, but instead am stuck with this.

Have you tried using a display port cable? I've heard that helps a lot.

Nevermind just saw you were using a display port, did you have any other displays connected?

This is very sad I was planning to get some display port cables to get around this issue..

Mine still gets unacceptably hot and noisy from just plugging it in to an external monitor with a USB-C to DP 1.2 cable.

Charging from my right side made things worse than the left. I have since switched back.

I don’t have access to the Apple Store since the COVID-19 restrictions, so I will need to wait to get my machine properly assessed. There is no good reason for its behavior.