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macrumors newbie
Original poster
Nov 13, 2020
Hello, after many days of research I decided to make a topic here and have more opinions from MBP 16 users.

Like a week ago I decided I need a larger screen for my macbook and I bought LG 27UL650 4K IPS.
I used at the beginning HDMI to USB-C for the connection. I went on the youtube to play a 4K video to see the quality of the video on my new display. After few minutes the fans start making lot of noise, I went to google check about the problem and I decided to try the Display Port and I bought a Display Port to USB-C cable for connection.

Same problem, fans start to be loud while playing a 4k video.
I turn turbo boost off ... same problem.

I’m using my macbook in clamshell mod and I have good air flow (I was testing on flat surface, and I have same results), I’ve done the nvram reset, test to check if the laptop have any issues and few more which were recommended by apple customer support through the live chat.

With the macbook on clamshell mode and without any video fans speed are around 1880rpm temperature 45/55 Celsius degrees, with youtube playing a hd video I have around 2200/2500 rpm and over 55 / 60 /65 Celsius degrees.

Playing a 4K video on youtube or offline I have after 1 min and 30 seconds over 3000 rpm and are still increasing and after 4/5 min of playing a 4K video I have max speed on my fans over 5620 rpm and a temperature around 80/85 Celsius degrees.

—edit: I was testing on multiple resolution and on 30Hz, 60Hz, 58.9Hz (or 59.8Hz I don’t know exactly) same problem.
—I didn’t notice the problem before because I didn’t had any external display but I notice few months ago overheating and fans noise while using google chrome and using the ipad pro 12.9 2020 as a second screen through air play, I solved this problem changing the browser to mozilla.

—GPU consumption is 5/6 W when I don’t play any video and 20W/30W playing 4k video in full screen.

16-inch MacBook Pro - Space Grey​
With the following configuration:
2.3GHz 8-core 9th-generation Intel Core i9 processor, Turbo Boost up to 4.8GHz
AMD Radeon Pro 5500M with 8GB of GDDR6 memory
32GB 2666MHz DDR4 memory
1TB SSD storage
16-inch Retina display with True Tone
Four Thunderbolt 3 ports
Touch Bar and Touch ID
Backlit Keyboard - US English
Accessory Kit​

I would like to have more options about this issue, if do you think is normal or no.

Yesterday after over one hour talking with customer support they decided to go with my laptop to a apple authorized service (my warranty finished on 2 December) and now I’m waiting to get a answer from them about this problem.

Do you think they will fix the problem?
Do you think they will give me the laptop back and I will have the same issue or worst different one? If yes what can I do in this situation while soon my 1 year warranty will expire and I don’t have Apple Care.

Kind regards and thank you in advance for the answers,
Last edited:


macrumors 6502
Mar 14, 2015
There is huge tread about external monitor connected and fan noise...

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