MacBook 16-inch Fan Noise

In my case the temperature goes up by 20 degrees just by connecting the external monitor but it starts getting really hot after 10/15 minutes (without doing nothing, not even browsing the web) and at that point the fans will start going crazy, sometimes all the way up to 5000 RPM with 0 apps or software running and CPU and GPU usage at less than 1%.

I know exactly 18 people that got a MacBook Pro 16-inch (from my office and friends, not here on this forum) and all of them are having the same issue, some of them had their machine replaced 3 times and they are still experiencing the same issue, 2 of them gave up and finally got a full refund.

In my particular case I was able to "partially fix" the problem by changing the refresh rate to 144 Hertz, so now I can use the computer for daily tasks and the machine is always at 40/50 degrees and the fans are at 1835 (left side) and 1700 RPM (right side).

I can make a conference call with zoom and I can watch a YouTube video without any problem.

There are still some issues there but I can live with them until a fix is available (Power Nap off, kernel panics, just to name a few).

My biggest concern is that the USB-C port where I got my external monitor connected since day 1, is gone (I don't know if it's related to the high wattage issue or not), so at some point I will have to take the machine to an Apple store for repair, but unfortunately right now I'm working at one of my offices in South America and I don't want to take the machine to an authorized dealer here, I will have to wait until probably next here to take it to an Apple Store in the US.

I keep thinking that this is a software/driver issue because I have tested all previous versions of Catalina (and the future version as well) and you can see that in every update they change the wattage consumption, so far 10.15.4 is the best one when using the 144 Hertz refresh rate. The machine will only use more than 6 watts when it really needs it, for example watching a YouTube video will use 9/10 watts, in other versions is always 20 watts or more. And when using 60 Hertz refresh rate is always running at 20 watts or more, even when the machine has 0 apps or software running.

MacBook Pro (16-inch, 2019)

2.3 GHz 8-Core Intel Core i9

16 GB 2667 MHz DDR4

AMD Radeon Pro 5500M 4 GB

Intel UHD Graphics 630 1536 MB

LG 34WK95U-W

Resolution: 6720 x 2834

UI Looks like: 3360 x 1417 @ 60 Hz

Framebuffer Depth: 30-Bit Color (ARGB2101010)

Mirror: Off

Online: Yes

Connection Type: Thunderbolt/DisplayPort

Regarding cables - it is the cable that came with the monitor and which was working with the previous MBP.

" I'm working at one of my offices in South America and I don't want to take the machine to an authorized dealer here"

Well if it's an authorized dealer then they are trained via certification from Apple to perform the same repairs the Apple store Genius Bar would. Why not take it to the authorized service center?

At this moment the fans of my MBP 16 "are at maximum (I suppose because the noise is strong). I use the dual monitor (that of the Mac and an external monitor). The external monitor is a 1920x1080 HDMI, connected with an adapter. The applications that I have started are: Whatsapp web 2.2017.6, Firefox 75.0 (no active video, simple web pages), Music 1.0.4.104 (Pink Martini, Sympathique :-)), some utilities like Caffeine, Parallels Toolbox ...

I hope these indications are useful for finding a solution, if it exists.

TY

P.S .: it is not worth getting angry for a PC, life is short and full of difficulties ...

:-)

Using

LG 34WK95U-W

Resolution: 6720 x 2834

...

Framebuffer Depth: 30-Bit Color (ARGB2101010)

At the data rate required to refresh that much data on the display, I do not see how you can avoid a fairly loud sound from the cooling fans, even if the only thing running were The Finder.

I also have the feeling that closing the clamshell would have no impact -- the fans would continue to be loud.

The only possibility would be to enter a much higher screen refresh rate, which appears to 'fool' the current display driver somehow.

6720 x 2834 is 19,044,480 pixels per refresh, at 30 bits per pixel, that's 571,334,400 bits per refresh, or 34,280,064,000 bits/second.

If your external display has mini DisplayPort or [Full size] DisplayPort input, using that instead of HDMI (using a third-party adapter) has sometimes been reported to generate less noise, esepcially when turning off the built-in display using Closed Clamshell mode.

Grant Bennet-Alder, thanks for the reply. Unfortunately, my monitor is a low-priced commercial monitor that I purchased only because it is large and has no mini DisplayPort or [Full size] DisplayPort input. I believe I will wait for the Apple update but I think, in any case, I will call support.

stefanosky wrote:

...

I think, in any case, I will call support.

An Excellent idea.

Be sure they do not consider it "solved" when they can't improve things -- insist on Escalation to a specialist or them filing a Bug Report.

The more users complain about a single issue, the more urgent it looks to Apple, and the more likely they will apply resources to fix.

Nevroze wrote:

...

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.

That sounds like a BUG.

Have you reported that loss to Apple support?

Hi!

I also use 16” Mbp for sound production and found a solution to calm down the fans.

there is a terminal command to manually switch off dGPU:

sudo pmset -a gpuswitch 0 

and if you want to switch the automatic gpu detection mode back:

sudo pmset -a gpuswitch 1

unfortunately, there is no way to run an external monitor using integrated GPU. But for me that is better than a lot of heat and noise, because of ableton using dGPU.

Those settings should be very similar to using:

System Preferences > energy saver ...

[_] Enable graphics switching ... (i.e, use Discrete graphics processor under load and when it seems necessary)

And as you observed, an External display REQUIRES discrete graphics processor.

I believe that they do work differently since if you deselect this checkbox in preferences your MacBook will always run on dGPU. If you select this checkbox, laptop will use dGPU only when it needs it (as described). After entering sudo pmset -a gpuswitch 0 in terminal, my MBP always runs on internal GPU.

And as you observed, an External display REQUIRES discrete graphics processor.

I was answering to the guy who was struggling with dGPU caused problems while using music production software even without external monitor.

"I was answering to the guy who was struggling with dGPU caused problems while using music production software even without external monitor."

I'm not sure which software that member is using but music production software is not GPU-dependent so it shouldn't activate the dGPU especially since you said there's no external monitor connected. I use Logic Pro X and it does not activate the dGPU.

Well, you seem to be a very lucky person, who never experienced any problems and whose hardware and software always works as intended. Take my congratulations.

A man is having concrete issues. So do I. I try to help him, not you. Can you leave any comment in this discussion without starting a dispute?

The fact that you did not experienced this type of behavior, does not mean that this behavior don't exists. If you open an empty project in Logic or Ableton, it won't use dGPU. But after populating your tracks with plugins it will start use dGPU in case if it's available. And a lot of people around the globe are having this issues. For Ableton it started with version 10, for example.

As I said two days ago, I have the problem of noisy fans in my 16" MBP even when I am not using high-performance software. I have installed iStat and what I have read is quite impressive. The Radeon graphics card consumes over 17W, more than half of all MBP, while the eight core CPU consumes only 2.5W. All this only with the second HDMI monitor and also with two different adapters (Thunderbolt-HDMI). If I disconnect the second monitor, the consumption of Radeon drops to 0.12W. I am convinced that with two or more monitors the DGPU is always active, even if you try to turn it off by Sys Preferences or with other methods (Terminal). The problem seems to definitely reside in the discrete GPU Radeon. I haven't found any solution so far, if not using only one monitor at a time.

:-(