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Unfortunately... nobody of you is either wrong or right. There is some serious messed up things going on with the dGPU drivers, and can be attributed to a lot of variants in displays, adapter, configurations. I did some testings, and here are the results. Please read until the end if you're really interested.


(...)

See that power value in “Radeon Pro 560X” section?
This is only with integrated panel. No app running except Finder.
14W/13w

this dGPU thing is like this since like forever. Hence my request for a iGPU-only 16 machine. No way I want to take this power penalty just because I need to use external monitor.
 

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Unfortunately... nobody of you is either wrong or right. There is some serious messed up things going on with the dGPU drivers, and can be attributed to a lot of variants in displays, adapter, configurations. I did some testings, and here are the results. Please read until the end if you're really interested.

For the last few days I played around with two different 32" monitors, to try to find the "coolest" option for my MacBook. I'm almost always in clamshell mode while docked, and I want the real estate of a 2560x1440 monitor on a 32" panel. The two monitors are both LG:

32UD99 (32" 3840x2160 - 60hz - USB-C)
32GK850G (32" 2560x1440 - 165hz)

I didn't really have a problem with the 4K monitor: Great panel, gorgeous sharpness, nice viewing angle etc. Thing is, I usually play a lot of media for work or entertainment, and I noticed that pushing around 2560x1440 in HiDpi (which renders at 5120x2880 and scales down to panel resolution) in an already hot enclosure made the fans spin up quite a bit. I did some testing using 2560x1440 on the same panel and especially when in full screen the difference in watt consumption was noticeable, but of course all the text was blurry because it wasn't using native resolution. I decided to order the 32GK850G, which is a little inferior in quality due to the VA panel, but at least it's a 32" 2560x1440, and decently rated.

The monitor comes in, and I'm excited to get back at using a single cable to dock. I'm using a standard USB-C dock with power pass-through, HDMI connection to the monitor, and jack for audio. Not so fast: the same system and dGPU that was easily pushing 2560x1440 using only 5W on the 4K monitor, now it's using 18W on a native resolution monitor JUST TO STAY IDLE on the desktop. Of course the minimum usage made the fans spin up like crazy.

Tinkering around all night with both monitors, and one USB-C to DisplayPort cable order later, I finally get the hang of it: the dGPU for some strange reason hates the HDMI connection (which can only go up to 60hz on that monitor) and uses 18W just to idle. But, when connected to with a proper DisplayPort cable instead of the USB-C dongle, it can properly interface itself with the monitor and give me the coveted 5W. The strangest part of all of this? If I select 2560x1440 60hz in the system panel, it still jumps up to 18W, but If I go 85, 100, 120hz with SwitchResX it goes back to 5W. That doesn't make any sense.

So here are some results at 2560x1440 85hz. There are six major steps in this graphs:

1. Clamshell, idle on desktop.
2. Clamshell, streaming from Safari on Prime Video (The Office S01E01) in full screen.
3. Clamshell, playing a 1080p, 12GB BluRay rip on IINA in full screen.
4. Clamshell, back to idle on desktop.
5. Clamshell, switching to "Default for display" resolution in the system menu.
6. Undocking and using internal monitor.


View attachment 889901

Ignoring the temperatures of the CPU which can vary by a lot of factors, one thing is comparable for all of our systems: watt usage. And you can see in the system total, that for some configurations, you can be burning 27W for staying idle on a 2560x1440 monitor while the internal monitor (which being HiDpi is A LOT more pixels) can be pushed, with all of the system, for just 3W. I also noticed that using different types of interface to the monitor can give more choices both in the system display setting and in SwitchResX.

By the way I still find strange, as per my last post, that something is firing up on the side you plug the monitor in, or even if you just plug in a USB device like a hard drive. While the 15" didn't fire up the Thunderbolt controller if there wasn't any Thunderbolt connection to establish, it seems that the 16" does even for USB. If the system undocked is 3,70W, and the dGPU in idle is 4,90W, there seems to be another 5W lost by powering the Thunderbolt chip, even if the monitor is just using DisplayPort through USB-C.

So, after all of this testing, and to go back at the replies above my advice to everyone is: play around with different interface connections to your monitor, different cables and different resolution/refresh rates. The dGPU at idle should not burn more than 5W even at 4K. The lowest system total I managed to get in clamshell, 2560x1400 was those 13,40W.

A lot of people make it seem like this is not a big deal, but it is: The system can push work extremely efficiently while on internal monitor, as low as 3W. This means a lot less heat generated and a healthier system, and more importantly, a healthier battery. While I find now "acceptable" idling at 13W, it still takes your CPU to around 50-52°C and the batteries at 34-36°C, which is uncomfortably hot for their health. Also, 13W on a 100W rated system, is like burning 13% of your thermal capacity for doing nothing at all.
Nice post. Curious if you've tried anything with the display being open also also connected to an external display?
 
Nice post. Curious if you've tried anything with the display being open also also connected to an external display?
Just tried internal + external. Seems to trigger that "18W" anomaly state at any refresh rate. That is way too much for two monitors idling.
 
created an account with macrumors to lend my voice to this. I am running a base model i7. sure enough, hot like crazy when connected to external monitors. istat telling me same thing - +18 watts to Radeon high side with my monitor set up (which is 2 Benq pd2500q monitors - both connected to my CalDigit ts3plus - one on display to display, another on thunderbolt to display cable). if I change to scale my monitors to be 1080p - the watt usage drops to 5w (where it should be). this clearly seems to be an issue with the drivers in the dgpu (or at least I am hoping).
 
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There are serious issues with the AMD 5XXX series in macOS Catalina 10.15.2, especially with METAL. Some of this may be addressed if it's a driver issue.

As for your CalDigit TS3 Plus, make sure you update the firmware to the latest. It apparently addresses several compatibility issues with MBP16,1 in addition to increasing PD to 87W.
 
There are serious issues with the AMD 5XXX series in macOS Catalina 10.15.2, especially with METAL. Some of this may be addressed if it's a driver issue.

As for your CalDigit TS3 Plus, make sure you update the firmware to the latest. It apparently addresses several compatibility issues with MBP16,1 in addition to increasing PD to 87W.
running the updated firmware for sure.
 
created an account with macrumors to lend my voice to this. I am running a base model i7. sure enough, hot like crazy when connected to external monitors. istat telling me same thing - +18 watts to Radeon high side with my monitor set up (which is 2 Benq pd2500q monitors - both connected to my CalDigit ts3plus - one on display to display, another on thunderbolt to display cable). if I change to scale my monitors to be 1080p - the watt usage drops to 5w (where it should be). this clearly seems to be an issue with the drivers in the dgpu (or at least I am hoping).

Yeah, another strange thing about that 18W state is that is not burning that power and scaling up based on what's happening on screen: it's 18W at idle, 18W playing a video, 18W browsing the web etc. While on 5W it scales up to 7W, 9W based on what's happening.
 
I know the pic below are desktop cards, but the Radeon Pro 5500M is basically the same chip as the desktop 5500 XT (Navi 14) running at much slower clocks to reduce the power. Notice how most of the Navi chips are using significantly more power than their Nvidia equivalents. There's either something wrong with AMD's drivers or hardware that's causing a much bigger spike in multi monitor configurations (which is what driving an external monitor is as you can't have the iGPU driving the internal while the dGPU does the external, or Nvidia is just much more efficient when driving more than one display)

power-multi-monitor.png
 
I know the pic below are desktop cards, but the Radeon Pro 5500M is basically the same chip as the desktop 5500 XT (Navi 14) running at much slower clocks to reduce the power. Notice how most of the Navi chips are using significantly more power than their Nvidia equivalents. There's either something wrong with AMD's drivers or hardware that's causing a much bigger spike in multi monitor configurations (which is what driving an external monitor is as you can't have the iGPU driving the internal while the dGPU does the external, or Nvidia is just much more efficient when driving more than one display)

power-multi-monitor.png

One of the best posts in this thread! Very enlightening, thank you very much.

Based on this information I believe Apple has two options:
- get back to Nvidia (not likely)
- launch a revised 16 with an entry level model with only iGPU (fingers crossed!)
 
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An obvious way to separate the MacBook and MacBook Pro lines would be to differentiate the machines with dGPU to the "Pro" line only and offer iGPU only machines on the MacBook lines. Cannot see Apple doing that in the short-term. The product line has too much overlap and seems to work to their advantage.

While we're on the wish list, would be great to buy an MBP16,1 "bottom portion" without the screen or dGPU with a Core i9 processor and 128GB RAM... or they could just update the MacMini/Pro.
 
I know the pic below are desktop cards, but the Radeon Pro 5500M is basically the same chip as the desktop 5500 XT (Navi 14) running at much slower clocks to reduce the power. Notice how most of the Navi chips are using significantly more power than their Nvidia equivalents. There's either something wrong with AMD's drivers or hardware that's causing a much bigger spike in multi monitor configurations (which is what driving an external monitor is as you can't have the iGPU driving the internal while the dGPU does the external, or Nvidia is just much more efficient when driving more than one display)

power-multi-monitor.png
The thing is that something is still funky with the driver. I just did a clean install tonight just to make sure I didn't mess things up using custom resolutions with SwtichResX, and while plugging in the external monitor, with a direct USB-C to DisplayPort cable to avoid issues with docks etc, the default 2560x1440 60hz resolution drives the dGPU crazy at 18W. If I force 144hz, which is more than double the frames, it goes back down to 5W.

I still didn't find a configuration which can drive internal + external at lower than 18W, but then again, that 18W seems to be some kind of threshold the dGPU is driven up to by the driver instead of actual workload.
 
I posted this somewhere here before but worth mentioning again

I tested mine in safe mode, open and with an ext monitor, at the suggestion of an Apple tech. The power draw for Radeon high side in safe mode was a consistent ~12watts no matter which configuration - no ext monitor, clamshell w ext monitor, or open with monitor.

out of safe mode it does the same ~5/~18 watt thing everybody else is describing

I think this is at least hopefully a promising indication that this is a software/driver issue and not a hardware issue. Hoping for a fix
 
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@Camarillo Brillo I understand your words, but why does it have to take so long? It's already 2 months now people are complaining but still no solution. I'm starting to think that this is a 'by design'issue'. (hope not....)

The same about the 'popping sound' issue at 44.1Khz. Still no solution.
 
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I have the 8 core 16" and don't have any problem with my 21:9 external monitor over thunderbolt 2. However my monitor isn't 4K.
 
I have those problems with 1080p display connected via USB-C to HDMI cable. 🤷‍♂️ 18W with internal + external no matter the load...

Base 6 core with Radeon 5300M
 
By the way, I gave a try to the Catalina 10.15.3 Beta 3 released earlier today... no dice, same behaviour with both my 4K and 1440p monitors.

On another note, I also tried plugging in a USB-C to Lightning cable, with no iPhone attached. Just the cable. The Thunderbolt side it is attached to still spikes +20°C and burns +4/5W of power in system total. This is like using the energy to charge an iPhone but instead wasting it by heating the inside of the unibody enclosure.
 
By the way, I gave a try to the Catalina 10.15.3 Beta 3 released earlier today... no dice, same behaviour with both my 4K and 1440p monitors.

On another note, I also tried plugging in a USB-C to Lightning cable, with no iPhone attached. Just the cable. The Thunderbolt side it is attached to still spikes +20°C and burns +4/5W of power in system total. This is like using the energy to charge an iPhone but instead wasting it by heating the inside of the unibody enclosure.

Thanks for taking time to post this, I was wondering if the latest beta would bring some improvements, it's a shame. Seems like we gotta live with the problem to at least .4, which sucks.
 
@Camarillo Brillo I understand your words, but why does it have to take so long? It's already 2 months now people are complaining but still no solution. I'm starting to think that this is a 'by design'issue'. (hope not....)

The same about the 'popping sound' issue at 44.1Khz. Still no solution.
I think that it has "always" been like this since they first implemented this dual graphics thing (all the retinas 15" have it since introduced, even the Nvidia Ones). This may have to do with how macOS handle's GPU Framebuffer with its own gmux system. But that's just a wild guess.
 
Hello forum, as promised, here are my actual measurements for my base core i7 machine.
As I wrote earlier, this machine is a keeper for me in contrast to the two core i9 I tested before.

No coil whine, a very low and not in any way disturbing "smearing" display which I don't really notice except when I look for it and the machine stays very quiet and I have no popping sounds.

I was sick the last days so I did not do much software development. When developing Java code with IntelliJ IDEA the machine kept quiet and only went loud when I did longer maven build jobs or ran extensive tests. That was to be expected and I am completely fine with that when the machine gets louder when under load.

In normal everyday usage it is very quiet most of the time, I have no complaints here. Here is a scenario of today where I am just chilling, watching videos, mailing, WhatsApp, ... So a scenario where this machine should keep quiet even when it is connected to a 4K monitor.

I am using for a test this 4K 60 fps video in Chrome which made the fans on the base core i9 machines I tested before go crazy:

This video plays with about 18% to 27% cpu load in chrome because Apple does not decode VP9 in hardware. But if you want to watch YouTube in 4k, you need Chrome.For all other web related things I use Safari.

I had Apple Mail open, WhatsApp, Finder, iStatMenus, Apple TV, Apple Calendar, Enpass and Magnet. So there were already some processes in the background but nothing intensive.

I connect my laptop to a huge LG 43" 4K monitor which allows HDMI, DisplayPort and USB-C input for 4K 60 fps signals. Thats why I do not really need the laptop display, the monitor is huge. So I can work in clamshell mode without problems.
I also put the laptop on this Boyata laptop stand which is basically only two narrow aluminium bars, so the laptop is basically free floating and getting air from everywhere or being able to vent air without being blocked and I think this also helped keep the fans silent.
These are the two test scenarios:
  1. the laptop connected to the original Apple 96W charger and connected to the 4K monitor via a USB-C to HDMI cable. I tested this in clamshell and with the laptop opened
  2. the laptop connected directly to my Caldigit TS3+ dock and getting power from there. The dock is connected to the 4K monitor via the same USB-C to HDMI cable I used in test. The CalDigit dock is using the latest firmware which increased the power output from 85W to 87W. I also tested this in clamshell mode and the laptop display opened
1. laptop not docked but in clamshell mode
directly connected to 4K monitor via USB-C to HDMI cable

lamshel direct connection.png
1. laptop not docked and laptop display opened
directly connected to 4K monitor via USB-C to HDMI cable

no clamshell direct connection.png

2. connected to Caldigit dock in clamshell mode
dock connected to 4K monitor via USB-C to HDMI cable

clamshell with dock.png

2. connected to calDigit dock laptop opened display
dock connected to 4K monitor via USB-C to HDMI cable

no clamshell with dock.png

So, in any scenario the machine works perfectly fine. When the fans keep silent when the machine is doing nothing intensive then I am completely fine with it and I don't care which value or which wattage is going up, thats Apples job to figure out :)

I hope this is helpful to somebody. It seems that there is no easy way to determine if a machine is very loud, has coil whine, etc. Maybe I was lucky? I sent back two base core i9 models and will now settle with the core i7 model although it has "only" 6 cores instead of 8 but that is already more than my Macbook Pro 2016 with 4 cores which I used before for software development.

The AMD Radeon 5300M is also fine. I am not often gaming on the Mac.I yesterday played Civilization VI on my 4K screen in 4K and it ran very smooth, impressive :) That will allow me to use my dedicated gaming PC less. I am not playing the latest games, usually only two/three years old games or elder. The difference to the Radeon 455 I had before is very very noticeable.

I still have one week to decide if I keep the machine but at the moment I am very satisfied with it, the battery endurance is very good (keep in mind that you should use Safari instead of Chrome for browsing!), the sound is excellent, I like the display. The keyboard is ok. My ThinkPad keyboards are much better but at least it hopefully is more reliable, my MacBook Pro 2016 butterfly keyboard had to be exchanged two times! I am also using a Macbook 12" 2017 and this butterfly keyboard I actually like a lot, very strange :-/

Greetings from Germany Janni
 
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Hello forum, as promised, here are my actual measurements for my base core i7 machine.
As I wrote earlier on this machine is a keeper for me in contrast to the two core i9 I tested before.

No coil whine, a very low and not in any way disturbing "smearing" display which I don't really noticed except when I look for it and the machine stays very quiet.

I was sick the last days so I did not do much software development. When developing Java code with IntelliJ IDEA the machine kept quiet and only went loud when I did longer maven build jobs or ran extensive tests. That was to be expected and I am completely fine with that when the machine gets louder when und road.

In normal everyday usage it is very quiet most of the time, I have no complaints here. Here is a scenario of today where I am just chilling, watching videos, mailing, WhatsApp, ... So a scenario where this machine should keep quiet even when it is connected to a 4K monitor.

I am using for a test this 4K 60 fps video in Chrome which made the fans on the base core i9 machines I tested before go crazy:

This video plays with about 18% to 27% cpu load in chrome because Apple does not decode VP9 in hardware. But if you want to watch YouTube in 4k, you need Chrome.For all other web related things I use Safari.

I had Apple Mail open, WhatsApp, Finder, iStatMenus, Apple TV, Apple Calendar, Enpass and Magnet. So there were already some processes in the background but nothing intensive.

I connect my laptop to a huge LG 43" 4K monitor which allows HDMI, DisplayPort and USB-C input for 4K 60 fps signals. Thats why I do not really need the laptop display, the monitor is huge. So I can work in clamshell mode without problems.
I also put the laptop on this Boyata laptop stand which is basically only two narrow aluminium bars, so the laptop is basically free floating and getting air from everywhere or being able to vent air without being blocked and I think this also helped keep the fans silent.
These are the two test scenarios:
  1. the laptop connected to the original Apple 96W charger and connected to the 4K monitor via a USB-C to HDMI cable. I tested this in clamshell and with the laptop opened
  2. the laptop connected directly to my Caldigit TS3+ dock and getting power from there. The dock is connected to the 4K monitor via the same USB-C to HDMI cable I used in test. The CalDigit dock is using the latest firmware which increased the power output from 85W to 87W. I also tested this in clamshell mode and the laptop display opened
1. laptop not docked but in clamshell mode
directly connected to 4K monitor via USB-C to HDMI cable

View attachment 890472
1. laptop not docked and laptop display opened
directly connected to 4K monitor via USB-C to HDMI cable

View attachment 890473

2. connected to Caldigit dock in clamshell mode
dock connected to 4K monitor via USB-C to HDMI cable

View attachment 890474

2. connected to calDigit dock laptop opened display
dock connected to 4K monitor via USB-C to HDMI cable

View attachment 890475

So, in any scenario the machine works perfectly fine. When the fans keep silent when the machine is doing nothing intensive then I am completely fine with it and I don't care which value or which wattage is going up, thats Apples job to figure out :)

I hope this is helpful to somebody. It seems that there is no easy way to determine if a machine is very loud, has coil whine, etc. Maybe I was lucky? I sent back two base core i9 models and will now settle with the core i7 model although it has "only" 6 cores instead of 8 but that is already more than my Macbook Pro 2016 with 4 cores which I used before for software development.

The AMD Radeon 5300M is also fine. I am not often gaming on the Mac.I yesterday played Civilization VI on my 4K screen in 4K and it ran very smooth, impressive :) That will allow me to use my dedicated gaming PC less. I am not playing the latest games, usually only two/three years old games or elder. The difference to the Radeon 455 I had before is very very noticeable.

I still have one week to decide if I keep the machine but at the moment I am very satisfied with it, the battery endurance is very good (keep in mind that you should use Safari instead of Chrome for browsing!), the sound is excellent, I like the display. The keyboard is ok. My ThinkPad keyboards are much better but at least it hopefully is more reliable, my MacBook Pro 2016 butterfly keyboard had to be exchanged two times! I am also using a Macbook 12" 2017 and this butterfly keyboard I actually like a lot, very strange :-/

Greetings from Germany Janni

Thank you for this extensive and detailed post Janni!!
Just yesterday I bought a USB-C to DVI converter to test my base i7 model, with my old monitor 22'' Samsung SyncMaster 226bw 1680x1050, before buying a new 27'' 2650x1440 one, cause from what said in this thread, only connecting an external display makes the fans go crazy.
I know it's a low resolution monitor but I want to test how my 16'' MacBook Pro reacts with external monitor connected, as I intend to use it in this way almost always (as I did with my old MacBook Pro too).
I hadn't the time for many tests but with the lid opened and playing a movie (from external HDD), a YouTube video (Safari 4+ tabs opened), and a song in iTunes (from 2nd external HDD), 1Password 6 running, I couldn't hear the fans at all. I have not bought any test app like iStats menu yet.
As I shut it down, the laptop was a little bit warm but not something worth mentioning IMHO...
I hope through the weekend to test it further.
 
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These are the two test scenarios:
  1. the laptop connected to the original Apple 96W charger and connected to the 4K monitor via a USB-C to HDMI cable. I tested this in clamshell and with the laptop opened
  2. the laptop connected directly to my Caldigit TS3+ dock and getting power from there. The dock is connected to the 4K monitor via the same USB-C to HDMI cable I used in test. The CalDigit dock is using the latest firmware which increased the power output from 85W to 87W. I also tested this in clamshell mode and the laptop display opened
Janni, great testing. Looking at the power figures and temperatures, everything seems to go up quite a bit when using the internal display. But the fans stay low, indeed.

Your post seems to suggest that power and heat stay under control using the 5300M GPU. So, is the problem limited to the 5500M GPU versions of the laptop? Does anybody have heat+fans through the roof using a 5300?
 
I have those problems with 1080p display connected via USB-C to HDMI cable. 🤷‍♂️ 18W with internal + external no matter the load...

Base 6 core with Radeon 5300M

Yeah same here absolutely ridiculous.

Hopefully we can find a way to disable the dGPU so we can use external monitors only with the iGPU to avoid this problem.

Either that or some driver to control the dGPU wattage
 
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