MacBook 16-inch Fan Noise

ahmedfromreservoir--

is the external display using DisplayPort/ThunderBolt/USB-C or a "legacy" interface such as HDMI?

My prediction would be that HDMI on the external display would cause hi wattage and hi temps with HDMI when built-in was also active, and Displayport on external display would allow low temp and low fans when built-in display was active.

The built-in display does not have its own screen buffer, so it will be seen as a "legacy" display requiring the "heartbeat" refresh -- the entire screen data, every 60th second, without fail or the screen will be partially blanked and the user will see it as flashing.

The code segment referenced on a GitHub page above show logic that checks for display TYPE, and if more than one display is a "legacy" display (and therefore require heartbeat refresh) the memory speed and power will be increased to be certain there is no loss of data with two or more displays requiring a heartbeat refresh, and very tight time constraints.

This appears to be what causes the power to be set to a higher level, and also explains why when the built-in display (by definition a legacy display) is turned off by closed clamshell mode, the remaining display(s) may use less GPU power if at least one of them is a directly-connected DisplayPort (or ThunderBolt, or USB-C) display that does NOT require the "heartbeat" refresh.

I think the problem with using a Dock is that the Dock may request DisplayPort Dual Mode, to ensure its data stream includes the heartbeat refresh, in case it has to support a Legacy display.

Executive summary: you can get the GPU power and fan noise lower if no more than one of your displays is a legacy display {HDMI, DVI, VGA}.

(the built-in display is a legacy display)

(most Docks will count as a legacy display regardless of how the actual display is attached)

It appears that when you attach more than ONE "legacy" display, the timing requirements to support the "heartbeat" refresh and still keep the screen from blanking are so high that the card shifts RAM to fast, high power mode.

The "heartbeat" refresh was used to maintain the data for CRT displays that did not have a Screen Buffer. The entire screen data must be fetched and sent to the display under strict timing requirements every refresh period (like 60th second). Otherwise, a portion of the screen will be blank for that period, and will be seen to be flashing.

"Legacy" displays are {HDMI, DVI, Analog VGA, and possibly ANY interface on some Docks} Also, the built-in display counts as a "legacy" display, so if you do not using closed clamshell, the built-in is your ONE allowed "legacy"display.

The rest of your directly-connected displays {DisplayPort family, ThunderBolt, USB-C} cause far less timing-sensitive load on display RAM, so the card often continues to run in low power RAM mode. (We do not het have enough data to answer definitely when low power RAM mode is precluded for other reasons.)

I think there's a solution. I took some advice in one of the forums. I installed SwitchResX and set my Dell U2715H monitor to 40Hz refresh rate. After that, in clamshell mode, the RHS went down to ~8W.

I think it's a miracle after all this.

For that particular setup I would suggest switching to HDMI. I have no idea why, but my tests suggest that for 1920x1080 @ 60hz in clamshell mode DisplayPort uses 17w and HDMI uses just 5w. Hope that helps as a temporary workaround while we wait for fix... if that ever happens.

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.

After reading through this thread and having the same issues as described in many many post here.

For me the only solution is at the moment:

• De-Activate Turboboost
• Use a laptop stand for the MBP 16

Especially the laptop stand was a great invest.

Without that stand my MBP reached around 3.500 rpm when using a Windows VM (office work). Since I used the stand the average is 2.500 rpm.

The stand just lifts the MBP for 15cm in the back, but the airflow seems so much better that I now can work with a nearly quiet Macbook.

Some update from my side. I purchased a Samsung C34J791 34" bend ultra wide monitor I connected it to the Thunderbolt 3 port through my CallDigit and I see the following behaviour:

• MBP 16" open + external screen + turbo mode on, dGPU takes 18-19watt, temp between 65-70C fans around 3500 rpm with an hour conf calls through teams temp raises to 100C fans go to maximum
• MBP 16" clamshell + external screen + turbo mode on, dGPU takes 5-8watts, temp between 55-65C fans around 2300 rpm with an hour conf calls through teams temp raises to 70-75C fans go to 2500-2800 rpm
• MBP 16" clamshell + external monitor + turbo mode off, dGPU takes 5-8watts, temp between 45-50C fans 1700/1833 rpm with an hour conf calls through teams temp raises to 50-55C fans stay below 2000 rpm

I must say I am happy that I can work with turbo boost off (I do not need it for day-to day work) and in clamshell mode 12 hours straight without noise from the fans because they have to cool the dGPU.

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.

:-(

stefanosky wrote:

...

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 have suggested many times on this thread:

Connect your displays with DisplayPort family, DisplayPort runs much cooler

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 AMD.

An upgrade about my situation with the 16" MBP fans.

As I said a few days ago, I have a MBP 16 with a second low quality monitor, an HP 27o (1920x1080) connected with the MBP through an HDMI and a USB C / Thunderbolt adapter. With this configuration the fans very frequently start at high speed, even before logging in (if I leave the startup screen for more than a few minutes)! Once I entered the system I installed iStat with which I can read the temperatures in detail of many internal components. In normal conditions, since the discrete graphics card is always on due to the second monitor, the overall temperature never drops below 65 degrees, while with some active process (for example: a download) the temperature reaches 100 ° rather frequently. In this case the fans rise above 5,000 RPM. I then installed Turbo Boost Switcher, as someone had suggested in this post. This widget allows you to turn off the microprocessor boost. With the boost deactivated the overall temperature never rises above 63 ° and the fans are fairly quiet (2500/2600 RPM). If I disconnect the second monitor and work only with that of the MPB and deactivate the boost, the overall temperature drops below 50°, sometimes even below 45°.

At first I thought the problem was due exclusively to the graphics card always on, now I think it is a complex of things that cause the high internal temperature. Certainly the boost has an important responsibility, which is why I will continue to use Turbo Boost Switcher, at least until Apple has solved the problem.

I hope this can be useful for someone.

Note: in normal conditions the MBP does not show any difference with or without boost, regarding the performances.

I've done the exact same thing, use turbo boost switcher and it's worked the same for me as you've described.

Fans not gone above 2,500 and temp not about 65 connected to 2k Dell monitor with thunderbolt to DP cable.

When not connected to a monitor everything runs way cooler anyway, 35/40.

As you say, I'm also OK to use this work around for now in until there is an official software update from Apple to address the issue, fingers crossed.

I'm just glad I can now listen to music at my desk with headphones without it sounding like I've got a hoover running on the desk too!

Did you happen to read the thread? There are many people who have found how to fix this but some have been pretty good solutions for the issue that have opened the door for more control over the system. Some have found that changing the port in which the computer is charged helped. Others have found that Turboboost doesn't really help with speed but it does with temperature but turning it off. For some the CalDigit TS3+ dock works well (that's what I use because it's easy to connect and disconnect from the office). Some have increased their external monitor to 85+ hz and that drops it down quite a bit.

If you are having issues and you know your machine is defective you really need to contact Apple Support. Do not wait.

I don't think 10.15.5 makes any difference with 10.15.4. The 5500M dGPU still consumes 5w with built-in screen and 18w using external 4K monitor on my computer. And, I don't think Apple will fix this problem anymore. I have called the customer service twice and submitted to engineers for review. They all gave me same answer saying "this is completely normal and designed as this way".

If you do think about using external monitor with built-in screen and cares very much about noises, try to grab i7+5300M version. It's quite cooler than i9+5500M. And rumors said UltraFine series monitors and high refresh rate monitors have better thermal performance too.