MacBookpro M1 max and external monitor flickering

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MacBookpro M1 max and external monitor flickering

Has a solution for intermittent flickering of external monitors been found. I tried all the typical solutions (cables, refresh rate, restart, color adjustment, etc) but nothing worked. At the moment it just went away on its own but I’m concerned it will come back. Have heard story after story about this. Using most recent version of Monterey OS. BENQ PD2725U monitor. Have one week that I can still return the monitor but I’m told of same issue with other monitors.

MacBook Pro

Posted on Sep 24, 2022 1:30 PM

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Answer 1

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mikew56 Author

Level 1

14 points

Sep 24, 2022 6:30 PM in response to mikew56

I am using a thunderbolt cable which is rather short. It is the one that came with the monitor but I would assume that a company such as BENQ would ship a hi-end cable on a monitor that is $900.

I will try your suggestion and try another. BENQ told me that there is a known issue with the M1 chip and certain monitors. I have googled the issue and have come up with many people having this issue with the BENQ PD2725U monitor and a few other high end monitors from other companies.

Very frustrating. Trying to reach out to Apple about it. I love this monitor except when this issue happens every once in a while.

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Answer 2

Sep 25, 2022 6:38 AM in response to mikew56

https://www.apple.com/shop/product/MQ4H2AM/A/thunderbolt-3-usb%E2%80%91c-cable-08-m

this one is rated for the required 40 G bits/sec needed to support that high resolution display in high color mode, which may be the only way it wants to work.

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Answer 3

Sep 24, 2022 5:09 PM in response to mikew56

That is a very hi color display at a very high resolution. It requires a LOT of bandwidth.

It requires high-end genuine ThunderBolt cables that are less than 0.8 meters in length. Otherwise, it may flicker or drop out entirely.

cables shipped in the box are often "lowest bidder" cables, and may not be good enough.

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Answer 4

Sep 24, 2022 6:53 PM in response to mikew56

That's not evidence of a defect, that's a random writing by someone who may or may not know what they are talking about.

The required data rate to support a display like yours is very close the the maximum switching speeds of digital logic. You (and probably the others on that MacRumors thread) need to be using top-tier ThunderBolt or USB-C cables, as appropriate. Those cables are Never more than 0.8 meters for Apple's best cable, and 0.5 meters typically.

It is not the length that is the defining factor -- the signals on ANY cable will not be crisp enough beyond that length on any cable. Newest Macs may now watching for issues reported back by the display, and blacking out can be telling you your cables are less than ideal for these conditions.

An experiment would be to reduce the number of colors, the resolution, or the refresh rate. I expect everything will be rock solid then. Any of these reduces the signaling rate required.

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Answer 5

mikew56 Author

Level 1

14 points

Sep 24, 2022 11:21 PM in response to mikew56

Thank you for your explanation. Do you know of a specific cable that meets the bandwidth you are talking about? And also how do lower the number of colors?

I appreciate you taking the time to respond about this.