MacBook 16-inch Fan Noise

igors192 wrote:

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Also will using just USB-C -> DisplayPort cable prevent so called "legacy" mode?

Yes, it appears that directly connecting a DisplayPort display using only an adapter (and not a dock) does not force the Discrete graphics chip into high-power RAM mode.

The Apple store sells a Moshi DisplayPort cable that is rated for "5K"

https://www.apple.com/shop/product/HLR62ZM/A/moshi-usb-c-to-displayport-cable

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In my opinion, Turbo boost is mostly specsmanship for most serious tasks. It allows one (or slightly more than one) processor to run much faster, but only when all processors are not engaged and already heating up the die.

Serious production software tends to already be heavily multi-tasked, so the incremental benefit of Turbo boost seems very ethereal to me. It only helps single-threaded operations.

executive summary: If low noise is important to you, turning off Turbo Boost for less noise is a good trade-off, and costs very little in overall performance.

pairadime wrote:

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But it doesn't add up I mean is when I'm running just the laptop screen with the Radeon (same windows), I'm averaging 6.50 W approximately. When I'm running the external in clamshell, I'm at about 5-6 W. So where does the other 6 come from when I'm running both?

When you run a DisplayPort family display, it uses a packet interface that has no specific timing requirements. Display RAM (for the Discrete GPU, which is the only one used to support External displays) can be run in low power mode.

When you an HDMI or the built-in display with it, those displays requires the "heartbeat" refresh. It is not directly the Power that is manipulated, it is the Speed of the buffer RAM. Heartbeat refresh displays requires that every pixel on the screen be sent to the display, each and every every refresh period, with precise and fairly tight timing. And that requires the buffer RAM to run at its full rated speed, which takes substantially more power to run the 4GB of DDR6 Display RAM at full speed. Full speed is needed to support the fast, tight timing required to run a heartbeat refresh display. So it powers its RAM up to full power, and THAT's where the extra power is generated on the display side.

Disconnect all the heartbeat refresh displays (such as by invoking closed clamshell mode) leaving only Displayport family displays, and the RAM can be run at the slower speed, and lower power.

Executive summary: want lower power on they discrete GPU? Use only DisplayPort (or ThunderBolt, or USB-C) displays. The built-in display is not a DisplayPort display.

Want lower power when not working hard on the CPU? turn off Single-processor Turbo Boost.

Hi,

I have now completed some testing comparing my old 15" MacBook Pro 2019 (i9 2.4GHz, 32GB RAM, 4TB SSD, Vega 20 graphics) vs my new 16" MacBook Pro 2019 (i9 2.4GHz, 64GB RAM, 8TB SSD, Radeon 5500 8GB). TL;DR is that the 15" did not exhibit this problem.

Testing with LG 27" 5K display at system idle:

2019 15" ~8.5W

2019 16" ~6.5W

Testing with LG 27" 5K and Dell U3017 (same results for USB-C to DP, or USB-C to HDMI both Apple and ALOGIC dongles):

2019 15": ~8.6W

2019 16" ~20W

If I opened the 15" and used it as a third display, there was no measurable change to the above. Being able to run three displays without the system screaming like a jet engine was surreal...

This is a 16" system specific issue, likely related to the Radeon 5500 drivers and how they are configured/set up to operate.

There was another issue I experienced which I believe to be related - in releases from 10.15.0 to 10.15.3, I had issues with UI lag, as if the UI in macOS was locked to 30fps or similar (only on external displays that were not my LG 5K) and has since been resolved in 10.15.4. I suspect this may hold some clues as to what the GPU is doing with some external displays.

Can someone please share any details with their AppleCare cases as I will now proceed to log a case with them on Monday as I can readily reproduce the issue.

Also want to mention another drawback - if you are doing video calls like Zoom, Google Meet or MS Teams then you might need to get into the habit of disconnecting your monitor during these calls as it becomes a nightmare.

Also I should say that I have not experienced any abnormal issues when not using a monitor - so if your workflow doesn't need an external display you will probably be fine.

Using

LG 34WK95U-W

Resolution: 6720 x 2834

...

Framebuffer Depth: 30-Bit Color (ARGB2101010)

At the data rate required to refresh that much data on the display, I do not see how you can avoid a fairly loud sound from the cooling fans, even if the only thing running were The Finder.

I also have the feeling that closing the clamshell would have no impact -- the fans would continue to be loud.

The only possibility would be to enter a much higher screen refresh rate, which appears to 'fool' the current display driver somehow.

6720 x 2834 is 19,044,480 pixels per refresh, at 30 bits per pixel, that's 571,334,400 bits per refresh, or 34,280,064,000 bits/second.

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.

Hi!

I also use 16” Mbp for sound production and found a solution to calm down the fans.

there is a terminal command to manually switch off dGPU:

sudo pmset -a gpuswitch 0 

and if you want to switch the automatic gpu detection mode back:

sudo pmset -a gpuswitch 1

unfortunately, there is no way to run an external monitor using integrated GPU. But for me that is better than a lot of heat and noise, because of ableton using dGPU.

DPJ wrote:

They may have you send it in for repair.

I don't think there are any reported case of Apple repairing this issue. Not sure why you are suggesting this?

I called Apple multiple times to complain about the excessive dGPU wattage. One personally told me that the fans on her own base 16" are louder than her previous 15".

Then I talked to three level-2 seniors and they told me different things. First guy said that the engineers are aware of the issue but can't say if its software-fixable or not, and actually hanged up the call while I was waiting for his research. Second guy said the engineers are not aware and to just return the Macbook if I'm not satisfied with. Third guy opened a ticket for me and will do a research for the status of the engineers awareness and will call me back monday before I decide to return this macbook or not.

With only a single 1440p@60hz monitor connected, either with HDMI or DP, clamshell or not, I get 19W.

This is a bug. Especially when people using the same resolution at a higher refresh rate gets 5W.

Casual web browsing with one 1080p video opened on a second monitor should not make the laptop runs at 70°C / 3000 RPM.

I'm returning mine.

Apple called me back to tell me that the only way to make their engineers aware is to either send a detailed report at www.apple.com/feedback or send the macbook for repair at an Apple autorised repair store (since Apple stores are still closed during the pandemic).

I explained that this is not a case-by-case issue, referring to this thread + the macrumors one. I pointed that some users already sent their devices to Apple not resolving anything, so the level-2 senior again suggested to just return it since they cannot promise a fix or even an acknowledgment.

I blatantly said that I could just re-buy one again and return it before 15 days again while returning this one, saying it would be simpler and more eco-responsible to just keep it while we all wait for Apple feedback. She agreed and honestly told me that Apple is more likely to take action if more people are returning their product. She just can't let me keep this one any longer if I want to return it when Apple eventually give us feedback.

The issue is present on ALL macbook pro 16". Connect it to an external display while keeping the lid open and its dGPU automatically consumes 18W+ on idle. This is half of the whole laptop wattage on idle. Unacceptable.

Hi all, I had this problem at first, when I connected an external monitor the fan noise went 100% immidiately, even when Idle. But then I found out if i close the lid, the computer becomes dead slient, and the CPU actually goes 20 degrees lower. I think it has to do with not needing to power the display of the macbook (even though I had it all the way dimmed, i think it still required GPU processing). Hope this helps someone!

I think I have found a solution. Not sure if it will work for you, but its worth giving it a try!

The problem: When I connected an external monitor the fans went 100%, even when idle.

Solution: If you are like me, and do not need the MacBook display, and instead use external displays, then all you have to do is close the lid. The computer becomes dead silent, the fans go to 10% and the CPU actually cools down by 20 degrees. I think it has to do with Mac not needing to power the display of the MacBook. Opening the lid and dimming the display doesn't help because I think it still requires GPU processing.

I really hope this helps someone! It helped me tremendously as I do most of my work on an external 4K@60fps display, and having the fans at 100% all the time was a deal breaker. With the lid closed, I'm working in dead silence, I can't even hear the fans. They only ramp up when I do heavy video editing.

I just installed 10.15.5 and is way worse than 10.15.4, when using an external monitor at 144 hertz with 10.15.4, the machine stays cool most of the time (50 to 60 degrees) and the fans are at less than 2000 RPM most of the time (If I change the refresh rate to 60 hertz, that's another story, the machine will get really hot and the fans will go all the way to 4500 RPM), but now with the new update 10.15.5 the machine is always at 75 degrees or more and the fans will start kicking in after a while, and the Radeon will use more power with 10.15.5 than it was using with 10.15.4. So the latest version is a no go for me, I will go back to 10.15.4 and I'll wait to see if 10.15.6 is better. I was hoping to be able to use the new battery management feature but it seems that it will have to wait.

I can confirm that this happens on mine too (16" + 4K monitor connected via TB3 to DP)

In clamshell mode, the spamming is gone only if the resolution of the external monitor is set to look like 3008x1692 or 3360x1890.

When using it concurrently with the internal display, there is constant spamming in any resolution, but it is greatly reduced if the external display is set to one of the two resolutions mentioned above. It seems that the internal resolution does not make a difference.