Twice as high: Temperature 16" Clamshell (closed) vs. normal (open) use.

Chronos___

macrumors newbie
Original poster
Nov 30, 2019
21
5
Göttingen
I got my 16" MacBook Pro (2.4 i9; 8gb 5500M; 64gb of ram) two days ago. Before I was using a six year old 15" MBP, which never had any problems temperature wise.

When I use the MacBook the normal way (opened, without being connected to anything) in university I get really nice low temperatures around 30 degree (=86 °F), which is even lower than my older Macbook. Strangely, at least when it's quit the fans still seem audible sometimes.
Now when I come home, I connect my MacBook to this HUB; which itself is connected to a 144 hz; 1080p screen, my keyboard and my mouse. Since I don't work on two displays the laptop sits closed (clamshell mode) on my desk when connected.

The whole time the 16" MBP is connected in clamshell mode - the temperature doubles. It's now sitting on constant 63 degrees (145 °F). The fans are audible the whole time, which ist especially annoying, since I sit near the MacBook and ist like some constant background noise.

My old Macbook never had any real difference between clamshell and normal use. It was connected to the same display, mouse and keyboard. The only real difference is, that my old docking station was active (with its own power source) - but I don't really now if that's explains the difference in doubling the temperature.


The picture shows the temp. in clamshell mode, will maybe edit later for "open" mode (but its simply the same values divided by two)
Bildschirmfoto 2019-12-05 um 17.49.26.png
 
Last edited:

MrGunnyPT

macrumors 6502a
Mar 23, 2017
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587
I found that certain Hubs cause temperatures spikes and even Kernel Panic attacks on my 16"... I'm really not sure what is causing all of this.

I do have some situations with temperatures when connected to external monitors and it's around 60-65c like you are reporting.
 
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andrewpsy

macrumors newbie
Apr 17, 2010
13
5
Does anyone know how to trick the post-2016 MacBook Pro to use external monitor only without entering clamshell mode?

With my 2015 MacBook Pro, I could place a small magnet over its left speaker so it "thinks" clamshell mode is activated therefore making the sole external monitor the only active display.

There are couple advantages to use it this way:
  1. laptop stays cooler compared to the clamshell mode because it dissipates heat better
  2. laptop doesn't need to power 2 displays (1 integrated + 1 external) so the overall performance is better and less work for GPU means less heat as well.
I tried the magnet trick on my 2018 15" MacBook Pro from work but failed to find a spot to trigger the clamshell mode. I will try the same thing with my 16" when it arrives.
 

mightyjabba

macrumors 68000
Sep 25, 2014
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Tatooine
You mentioned that you get very low temperatures when not connected to anything, but have you tried being connected to the screen and other peripherals but not in clamshell mode?
 

Chronos___

macrumors newbie
Original poster
Nov 30, 2019
21
5
Göttingen
Bildschirmfoto 2019-12-05 um 18.27.33.png

This was the temperature when having the hub connected but the MacBook open. The fans were a lot slower, but temperature was still around 63 degree. (Still double of what I get when no HUB connected)

- Sadly I can't connect my screen and the peripherals without the hub, since I don't own fitting dongles for this.

It would be interesting to see if other 16" users got the same problem, because I expect a lot of people using different kind of hubs/docks.
 
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mightyjabba

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Sep 25, 2014
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I’ve been getting around 60 degrees with 3 screens and other peripherals connected in clamshell mode but the fans aren’t running (or at least aren’t audible).
 

Chronos___

macrumors newbie
Original poster
Nov 30, 2019
21
5
Göttingen
I’ve been getting around 60 degrees with 3 screens and other peripherals connected in clamshell mode but the fans aren’t running (or at least aren’t audible).
Are you using some kind of dock or do you connect them directly to the MacBook?
 

mightyjabba

macrumors 68000
Sep 25, 2014
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I’m using a USB-C dock for one HDMI connection and USB A peripherals, and the other two displays are connected directly.
 

Daverru

macrumors newbie
Dec 5, 2019
13
11
I think the reason of high temperature is not the clamshell mode, but an external monitor.
With any connected monitor MBP always switches to Radeon GPU, which consumes much more power than integrated Intel GPU, so it makes the laptop much warmer.
 
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impulse462

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Jun 3, 2009
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these temperatures are normal while connected to an external display. you know the computer is rated to get much hotter than this...
 

Chronos___

macrumors newbie
Original poster
Nov 30, 2019
21
5
Göttingen
Bildschirmfoto 2019-12-07 um 11.55.43.png

With any connected monitor MBP always switches to Radeon GPU, which consumes much more power than integrated Intel GPU, so it makes the laptop much warmer.
Would explain it.This picture shows the temperature without clamshell and peripherals connected. The GPU is a lot cooler, but also the CPU are "half as cool" which is strange.




these temperatures are normal while connected to an external display. you know the computer is rated to get much hotter than this...
Yeah, I'm not concerned for my computer (the battery stays at comfortable 30 degree), its just annoying because when at home I always work with a Display, keyboard etc. connected. Also my six year old Macbook is capable of staying quite when I used it the same way.
 

petterihiisila

macrumors regular
Nov 7, 2010
129
62
Finland
Maybe the old MacBook doesn't have a dedicated GPU, and so there's no second chip pulling its own significant power? Try to run Heaven benchmark and have Activity Monitor's GPU History (CMD-4) on. You'll see two rows (in my 16" i9 it's Intel and AMD), if there's two GPUs. During the benchmark, the AMD GPU will spike. And fans go haywire.

I manage desktop noise with Turbo Boost Switcher. When the fans hit 5k, I turn Turbo Boost off until they're back to 3k. That way I get nice boost performance for a good while, but don't have to listen to the fans for long.

In my line of work the fans rarely hit 5k though. And when Turbo Boost is off, there's 8 cores that generate nice performance at a stable 2.3 GHz. There's no stutter or other concessions to general user experience.

When the battery is not charging, I run Turbo Boost off all the time. Fans don't spin up, and battery life is significantly better. I know I'm losing some peak performance, but that same peak performance would eat battery faster than I can get more coffee. Unless I'm in a hurry and every minute costs money, I'll let the cores work at 2,3 GHz and wait a minute longer. And then can still work an hour or two longer.
 

niho

macrumors member
Dec 7, 2019
43
46
I'm having exactly same problem. Fans always loud, around 2600rpm when I connect to external monitor.
 

katastropoulos

macrumors newbie
Dec 8, 2019
21
20
Germany
I am having the same problem. 2,3 GHz 8-core Core i9 with Radeon 5500M 4 GB.
when I connect it directly to my 4K external Monitor or via my CalDigit TS3 Plus Dock the fans ramp up significantly although the CPU load is quite low. Especially watching YouTube videos in Chrome lets the laptop get quite loud. CPU load when I play 4K 60 fps videos in Chrome is about 14%. Nothing that should stress such a powerful machine :-/

The Macbook Pro 15 2016 I was using before was much more silent than my Macbook Pro 16" :-(
I am not sure why this is.

I am not doing anything CPU intensive the last days, just surfing the web, writing emails, ...
I will start heavier work like software development, virtual machines, etc in the coming week and hope that the machine will not get too loud.

I thought that improved thermals would also allow the machine to stay silent for a long time.

I don't know if anyone who uses the last BETA of Catalina 10.15.2 noticed an improvement in fan control? I am also suffering from the popping sound issues on my MacBook.

I can still return the machine. When the problem is the 8-core and the 5500M, I think I could switch to the 6-core and 5300M when this allows for a much more silent operation.

For my uses cases the 6-core and 5300M is fast enough. I only got the 8-core because I got it cheap in an Amazon black friday deal :)

Does anyone have a comparison between the fans in the 6-core/5300M and 8-core/5500M configurations? I could not find such information until now.
 
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Pepe4life

Suspended
Nov 15, 2018
396
3,411
I’m using the official Apple multiport adapter with a 4K screen connected to my 16” in clamshell mode. The fans are silent unless I’m gaming or video editing
 

beppedessi

macrumors regular
Sep 9, 2013
116
98
Impruneta (FI), Italy
Really interesting. Next week my new Gigabyte Aorus AD27QD will arrive, so I will be able to try "open" mode and "Clamshell" mode connecting the monitor to my MacBook Pro 16" trough DigitCall TS3 Plus. I will let you know the result!

P.S. just a little typo in the post "but I don't really Know if".
 

PROFESS0R

macrumors 6502
Jul 30, 2017
333
304
Same here. I run four screens in clamshell mode with a TS3+ doc, and I cannot hear the fans. Temperature are around 57 C now. House is at 20C.


I’ve been getting around 60 degrees with 3 screens and other peripherals connected in clamshell mode but the fans aren’t running (or at least aren’t audible).
 

MrGunnyPT

macrumors 6502a
Mar 23, 2017
986
587
I think the reason of high temperature is not the clamshell mode, but an external monitor.
With any connected monitor MBP always switches to Radeon GPU, which consumes much more power than integrated Intel GPU, so it makes the laptop much warmer.
Yeah I have been manually switching to the iGPU when I'm connected to an external monitor on battery to save some battery
 

katastropoulos

macrumors newbie
Dec 8, 2019
21
20
Germany
Very interesting. I did a PRAM/NVRAM Reset and a SMC reset on the machine. Now it is much more silent.
I am using it docked to a Caldigit TS3+ Dock and a 4K Monitor.

The temperature in clamshell and non clamshell do not differ a lot, here are some screenshots.
Left image is the laptop in opened state, the right image is in clamshell mode.
There is not a significant difference in my case. I am really starting to like this machine a lot.
When the popping sound issue is really solved with Catalina10.15.2 then I am completely satisfied :)
These results obviously are not longterm results. But based on that I will not return the machine, I had already contacted Apple and they told me to send the Macbook back via Amazon where I bought it via a black friday deal, that should not be necesary anymore :)

Laptop in clamshell.png
Laptop opened.png
 
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Daverru

macrumors newbie
Dec 5, 2019
13
11
manually switching to the iGPU when I'm connected to an external monitor
But how?:) I cannot find the way to do it. I'm trying to use gSwitch to force the MacBook to use only internal GPU, but it doesn't work while an external display is connected.
 

Daverru

macrumors newbie
Dec 5, 2019
13
11
I did a PRAM/NVRAM Reset and a SMC reset on the machine. Now it is much more silent.
You have "Radeon High Side" = 7.23W on the left picture. Could you please check is it really like this with an external display connected?
In my case Radeon always consumes about 18W while the external display is connected. Which is, i believe, makes the whole system so hot.
 

katastropoulos

macrumors newbie
Dec 8, 2019
21
20
Germany
Yes, I am working with an external 4K monitor via a Caldigit TS3+ Dock.

The laptop was in sleep mode for some time. Now when I came back and woke it up, it did not show a picture on my external display, I had to pull the Thunderbolt 3 Dock cable out of the laptop and reinsert it in order to get an image on the monitor :-/

At the moment, iStat Menues states 19,xx Watts for Radeon High Side, interesting.
Why is the value fluctuating that much? I am only surfing the web at the moment, I have Chrome and Safari open, no videos are playing, CPU load is 3%.

After closing Google Chrome completely I could see in the activity monitor that there is no application that needs high performance graphics. But the Radeon High Side value ist still 19,xx Watts.

I cannot interpret this. But the Macbook is still silent, fans at about 1700-1900 rpm.
Bildschirmfoto 2019-12-08 um 20.39.18.png
 
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Chronos___

macrumors newbie
Original poster
Nov 30, 2019
21
5
Göttingen
I’m using the official Apple multiport adapter with a 4K screen connected to my 16” in clamshell mode. The fans are silent unless I’m gaming or video editing
Can you measure your fan speed? It would be interspersing to see if it really is the hub which is the bottle-neck.

I cannot interpret this. But the Macbook is still silent, fans at about 1700-1900 rpm.
Maybe an active dock is still better than a passive one (hub) after all.

Maybe the old MacBook doesn't have a dedicated GPU, and so there's no second chip pulling its own significant power?
In my line of work the fans rarely hit 5k though. And when Turbo Boost is off, there's 8 cores that generate nice performance at a stable 2.3 GHz. There's no stutter or other concessions to general user experience.
I don't know if Turboboost switcher has 64bit option for Catalina. Also the CPU doesn't seem to be the cause of the heat, since its only running at 4-6%. The Radeon 5500M turn automatically on when you connect an external display and I haven't found a way to disable it.
 

MrGunnyPT

macrumors 6502a
Mar 23, 2017
986
587
But how?:) I cannot find the way to do it. I'm trying to use gSwitch to force the MacBook to use only internal GPU, but it doesn't work while an external display is connected.
Oh really? Damm that explains my battery usage lol
 
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