MacBook 16-inch Fan Noise

As someone who posted relatively early in the life of this thread about excessive thermals / fan noise caused by high power utilisation in the dGPU, I thought it might be good to provide an update.

I recently bought a CalDigit TS3 Plus docking station, mostly for the convenience, but also with a vague hope it might help with this issue. It has not. But some interesting observations nevertheless:

• With a 4k60 monitor connected using USB-C to HDMI 2.0 cable directly (no CalDigit), dGPU sits at 20 W power consumption when idle. Temperature / fan noise issues follow as observed by everyone else here
• Connecting the CalDigit and connecting to the same 4k60 monitor using the same USB-C to HDMI cable to the CalDigit, dGPU power consumption remains 20 W. Temperature / fan noise issues remain
• Similarly, connecting the CalDigit and connecting to the same 4k60 monitor using the a DVI to DVI cable to the CalDigit, dGPU power consumption remains 20 W. Temperature / fan noise issues remain

Different resolutions / refresh rates make no difference.

Probably no surprises there. But a couple of further observations I found interesting with the CalDigit connected and the monitor connected to the CalDigit, but the monitor turned off:

• The dGPU remains activated - gfxCardStatus is not able to switch to the iGPU
• Usually, dGPU power consumption is around 5 W, same as with running on battery standalone
• But sometimes, dGPU power consumption is higher, even as much as 20 W
• This issue seems to happen much less frequently if the monitor is connected to the CalDigit by DVI

In my mind, this is another data point on misbehaviour of the dGPU.

These observations also extend to leaving the MBP connected to the CalDigit with the lid closed and the monitor off (that is, I have plugged in the MBP to charge). I've come back a few times and found the MBP surprisingly hot, and after turning on, I can see that dGPU power consumption was high while "asleep", per the above observations. That's not good.

For reference, I have MBP 16", 2.3 GHz 8 core i9, 5500M with 8 GB VRAM

What I really can't understand is (I know this has been mentioned before):

1. Why the dGPU has to be run at 20W as soon as an external monitor is connected.
2. Why the CPU goes from about 1,70 GHz frequency to 3,73 GHz frequency when an external display is connected (as shown in Intel Power Gadget). Temperature goes from about 40C to 73C (almost doubles).
3. Summing up, why does the computer has to work so hard after an external display is connected. Does not make sense...

So I recently updated to 10.15.4, and offer a few observations (none positive, unfortunately):

• For me, fan noise and 20 W dGPU power consumption at idle are the same as 10.15.3
• Almost daily, I'm getting kernel panics when I open the lid of my MBP in the morning after having closed it in the evening. This is when connected to a CalDigit TS3+. This never happened in 10.15.3
• Irritated by this, I attempted to use CalDigit's firmware updater to update the firmware (I hadn't noticed it was out of date), and the process failed. CalDigit support confirmed that their updater has been neutered by the 10.15.4 update (they tell me it worked in previous versions)

So I'm pretty frustrated right now. It's been a long time and no sign of hope whatsoever.

Hey there, I have the same issues.

My MBP 16":

• i9, 2.3 GHz
• 16 GB RAM
• AMD Radeon Pro 5500M 8 GB
• 1 TB SSD
• macOS 10.15.4

Without any monitor plugged in everything works fine, temperature for Mail and Safari at 40°C, fans between 1600-1900 rpm. I've tested with the following monitors, lid open:

• LG 27UL850 4k, USB-C, HDMI and Display Port
• An very old Fujitsu (think 22") with resolution 1680x1050 pixels, HDMI and Display Port

--> Everytime the same result

• Temperature goes up to 75-90°C
• the fans stay at ~2700rpm.
• dGPU at permanent 18-19 W

I'm irritated with the permanent 18-19 W. Is that really normal when pluggin in an external monitor? I played around with the option "Automatic graphics switching" in the "Energy Saver" settings. If I do not plugg in a monitor and turn the option off, so that the MBP only uses the dGPU, the power consumption varies between 4 and 13 W. Wouldn't that be the same with a monitor plugged in?

I think this can help us get to the bottom of the issue.

Please observe GPU memory clocks. I'm not sure why your current figures are identical, but the average shows 288Mhz mem for the internal screen and 1472Mhz mem for 2 screens connected. Seems to be running at its max frequency.

Please do some further oberservations regarding memory frequency and GPU ASIC power.

Try this:

1. HWinfo has a log functionality (bottom right), before moving to the next step turn it on and save the file somewhere.
2. Test 1: Have your MBP sit idling for about 15 min. Make sure your screen won't go to sleep during that time. Do this from a fresh reboot without any programs open other than HWinfo.
3. Stop the test and safe the file. It will create a text file which you can use to create a graph for GPU memory clock + ASIC power current (!) over time. If you can't do it, I can do it for you.
4. Do the same connected to an external LCD + your internal LCD both running.

Thank you.

Refresh rate is a part of the timing. Timing also includes the total number of pixels (both visible and blanking). GPU can only change its memory clock when all monitors are in blanking intervals. Otherwise the screen will flicker. You can find out more about your timing information of your monitors by looking at the EDID of your displays.

Could you share the GPU memory clock rate with GPUZ under BootCamp for:

• built-in monitor only
• clamshell
• both

Thanks.

So I think I understand this pretty well. My point is that there are really only 3 meaningful combinations, and I can't find any evidence to support the idea that the interface makes a difference. What I see is:

• Internal monitor only: ~5 W
• Internal + external monitor: 20 W
• External monitor only: ~ 6 W

I cannot find any combination of resolution, refresh rate, mirroring, same settings between internal and external, different settings between internal and external, interface cable, dock, no dock, any of it, that makes any difference. And believe me, I've tried every combination I can think of. The only defining characteristics (for me) are the three dot points above.

I get the theory, but it just doesn't seem to make a difference in practice.

According to below post from another forum, the only solution to get it to 5W, is to use USB-C->Displayport Cable with higher than 60Hz refresh rate of your monitor. So just cable will not solve your problem if you are on 60HZ monitor.

Given that fact, we can fix it by purchasing new display and bloody cable :)

Can be another 500-1000$ bucks to invest, and given Apple lead times for fixing and reacting, probably worth it ... to forget for year or so....

They didn't fix a thing, all the symptoms of flawed drivers are still there, I still get 18W with:

• 2560x1440 60Hz USB-C > Displayport Cable - Clamshell
• 2560x1440 60Hz USB-C > Displayport Cable - Open Lid
• 2560x1440 60Hz USB-C Hub > HDMI Cable - Clamshell
• 2560x1440 60Hz USB-C Hub > HDMI Cable - Open Lid

Tested on 10.15.4 Supplemental, 10.15.5 Beta 1. Kext versions haven't been touched since last year. As said in previous posts my only way to get it down to 5W is actually using the direct USB-C > Displayport Cable and upping frequency to 85-100-120-144Hz which is not an option on most monitor. Reports of 10.15.5 Beta 1 in the previous posts are flawed since disabling HiDpi through SwitchResX actually lowers resolution and is not suitable for most monitors.

Working in Logic Pro X, simple 4-track project, simple plug-ins like sample delay:

1. Using only MBP display: around 60C average temperature.
2. Using MBP display + external display connected via USB-C to displayport: 80C average temperature. Feels really hot. With continued use in Logic... fans kick in.

Again, never had these issues with Late 2013 15 inch MBP. And yes, this is odd and needs fixing: drivers or MacOS or whatever.

"Every company in the world is in business for the same reason, to make money. Not sure why you needed to mention purchasing Apple stock or that you love Apple?"

People are saying that "Apple will take care of it" and "they haven't addressed it because it's not a problem to them" and I replied with examples of when they never replied(keyboard), examples to when they had to be class action sued(numerous), and to when they finally addressed something years after the fact. My point being, they are a corporation like others, and their debt to shareholders is to make profits not go out of their way to take care of customers. They will take care of them in so far as to prevent not taking care of them impacting the bottom line, be it through lawsuits or reputation hits, etc.

And I say that s a huge Apple fan, I think they've changed the world and will continue doing so. But like, I don't blindly follow them and expect them to catch me when I fall back.

"Not necessarily to you paradime but just info from my experience."

Great post. I think what's muddying the waters here is that there are 2 distinct groups participating in this very large thread.

1. People genuinely experiencing problems such as full blast fans for no reason, GPU artifacts, etc.
2. People concerned about the amount fo energy being used when an external monitor is connected out of clamshell mode. Concerned about battery life, concerned about longevity, etc

So far the concensus to these issues are

1. Return the machine and/or contact Apple about warranties and repairs.
2. Wait and see if Apple will address non-clamshell energy use in further updates.

Both of those consensuses, as far as I know, has Apple not admitting to issues. The first scenario can be argued to be anecdotal, as you said, millions of these are sold and it's impossible for all of them to be perfect, especially when considering their complexity. The second scenario can be argued to be systematic, as all16" MBP's are behaving the same way with external monitors.

Now add in the people that are saying that some of these issues are not actually issues... as in it's a feature not a bug, and we're in the seemingly opaque waters that we're in.

This MBP 16 has changed my usage behaviour:

• Shut down the machine every time I leave it for a while and overnight.
• Disconnect monitor when on video calls.
• Run with less open apps and less browser tabs.
• Reboot when it is consistently too hot and doesn't cool down.

I never had to do this with pervious notebooks from Apple, and I've had many. I don't think that anyone can argue the above behaviour is normal.

If you want to use the MBP 16 with a monitor without any issues then I can't recommend it. Here are some things that I have experienced first hand when using the MBP 16'' with a DP monitor:

• Great amounts of heat and loud fan noise when idle.
• Graphical issues - seems to happen when heat gets too much when running apps.
• Lagging input from keyboard and mouse, apps slow to launch and unresponsive - again when hot
• When it gets really hot - unresponsive touch bar
• Can't leave the computer in sleep mode overnight anymore as with previous MBPs
• Often need to reboot to let the machine cool off.

As you can see these issues are not critical, I have not experienced a thermal shutdown, however if i knew that I would have to put up with all these problems I would not have made the purchase. The performance is not what you would expect from a modern device.

"I am even thinking about if it would be the smaller problem to buy a 2019 15,4“ MBP, but there is still the issue with the butterfly keyboard."

Well, I could not recommend this either, I had my keyboard replaced more than once for 1 or 2 sticky keys. Had it not been under Applecare the cost is huge as they replace more than just the keyboard.

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.

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.