MacBook 16-inch Fan Noise

I just noticed that when I changed my external monitor resolution to 1080p from normal 2560x1440 Radeon is powered only by 3.5 Watts. Temperatures are falling down to normal levels (like when working without external monitor.)

Can anyone confirm that it is working on his mac?

When I select any other, higher resolution it goes to 16.5 - 17 Watts.

papsa wrote:

I'm start thinking that the best what we all can do now is to inform about the issue as much media / blogs / YT channels as we can.

It's odd that every single review I read about this mac said nothing about external monitors. I suppose that they don't event tested it so they didn't notice any issue and this is why there is no info about this issue in media.

Maybe when media will start talk about issue this would force Apple to do something because it's 3 months from the release...

I was thinking about highlighting this issue to some popular tech YT channels e.g Linus Tech Tips. I'm sure they would be more then happy look into this and make a video about it.

I have a new i9 and i can hear the fan when using it on my couch. not very loud but with my old 15 i never hear it. so i start to using my old macbookpro 15 late 2013 again for leasure stuff. and the new 16" only in the office …

Max Tech did an amazing video and it was posted here. He covered all points. Sadly some members here had the nerve to criticize his work. He's an independent YouTuber that does some of the best (if not the best) Apple tech reviews. He's not a corporation so criticizing and nitpicking his video was silly to me. No one here pays him to do the hard work he does. If people feel Max Tech missed some points then they should create their own YouTube videos and address the issues with their MacBook and provide solutions for the forum. He works free to help us and has been posting here offering more solutions on this topic and some people here still act entitled.

So today I left the mac doing nothing, came back and the CPU PECI temp is beyond 90c CPU usage is below 5% the machine is not doing any tasks. Rebooted and it it's cooled down a bit but still fairly hot.

It's running hot with the monitor consistently but also seems to spike really high for no reason from time to time. Spotlight indexing is turned off and nothing high shows in activity monitor.

I will go to an Apple store this week as I don't seem to be getting anywhere with the online support at this moment.

As a note: I'm using Turbo Boost switcher to disable the Intel Turbo Boost mode, this is not making any difference to the temperature as none of the processes are even pushing the CPU a little bit. I think this confirms that this issue I am having is a problem with the Discrete GPU and it is nothing to do with the CPU.

I'm not really seeing much difference in the temperature when switching between the lowest and highest resolution. I can see that the Radeon High Side is about 19w on the lowest and about 19.5w on the highest, so a slight difference in power.

One thing that keeps that Discrete GPU HOT is using a "legacy" display interface, such as HDMI. "Legacy" display interfaces feature the old CRT "heartbeat" refresh. They resend each and every pixel on the screen every refresh period, and the data rate at high resolutions means a LOT of pixels are re-sent 60 times a second. Sending all that data 60 times a second generates heat, and for nothing.

If your display has a DisplayPort family interface, there is a screen buffer in the display. Once the screen stabilizes, only the changes are sent. When the display stops changing, the link goes nearly quiet, and far less data sent can mean far less heat generated.

So I would expect that reducing resolution when using a "legacy" interface would reduce heat, possibly in a measurable way, and reducing resolution when using DisplayPort family would make no discernible difference (because you are already 'doing the right thing' by using DisplayPort family).

Let's not forget the Battery Issues. I got mine last week and the battery life is less than 5 hours. Ive done two support calls and there is no fix, yet. I need a Mac so I guess I will wait for a fix which is surely coming. For a $2500 laptop this is unacceptable Apple!

My comments were general in nature, and only triggered by the mention of reducing resolution seeming to reduce generated heat, not by actual laboratory measurements.

Keep in mind that many users here are asserting that the display chip is not operating properly, using too much power and generating inappropriate amounts of heat.

if you are using DisplayPort family and still see a reduction in power when reducing resolution, perhaps a malfunction in "Dual Mode" (that creates the "heartbeat" refresh data) may be one of the ways the discrete GPU is generating too much heat and using too much power.

I'm using USB-C Display Port, the reduction in power is very minor really and for me the temperature doesn't seem to change when lowering the resolution.

I also added a connected Ipad into the mix with sidecar as an extra screen and it doesn't raise the temperature anymore.

Thanks for the additional information, if that's the case, then is not working on the MacBook Pro 16-inch, so this is another proof that the GPU on the machine is not working as expected and is either a software or hardware issue. I still think is a software issue, because if I use the machine without an external monitor connected I can use the machine running different apps at the same time (even some that requires GPU and CPU power) and the machine is dead silent, so it's not logical that by connecting an external monitor and just browsing the web while the CPU and GPU usage is less than 3% the machine will get so hot and the fans will go crazy.

The built-in display uses the Integrated GPU for most ordinary purposes.

There is no pathway from the integrated GPU to the external display output -- connecting an External display REQUIRES the Discrete GPU.

No dispute, he does a great job and we are grateful for his work.

Sorry, DPJ, but we do not need to create our own YouTube videos if we pointed out that he missed an important point in his video regarding our problem. I shouldn't have to fight hot air from my computer and a loud fan because I plug in a 4K monitor with the lid up.

I think I may shoot my own video for this, and demonstrate specifically what happens so you can see it.

Thanks for spending your time posting here; I can't help but notice that you didn't try to replicate our issue as I requested, but you do contribute by posting notes like the one above.

You really add a ton of insight for me, and set a high bar for altruism by helping people on the discussion boards. Keep up the good work!