Dual 4K setup cannot downscale

I have a M2 MacBook Pro that runs Ventura. My desktop monitor setup is dual 4K @60hz, where the content is very small. With my previous intel MacBook Pro running Big Sur, I just downscale both monitors to 1440p (2560*1440) @60hz.

However, this no longer works with my new M2 MacBook Pro running Ventura. I can always downscale only one of the monitors to 1440p, @60hz, but cannot downscale the other: it is either 4K@30hz, or 1080p@60hz.

Tried some of the software (BetterDisplay, etc. ) but does not work.


Is this an apple silicon thing? Is there any workarounds? just can’t believe it worked on my crappy intel, but not in the fancy M series.

Posted on Aug 24, 2023 4:37 PM

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2 replies

Aug 25, 2023 1:03 PM in response to Xiangcai17

Hello dfsafa,


Depending on which specific M2 MacBook Pro you are using, the hardware technical specifications for your external monitors are as follows:


"MacBook Pro (2023) with M2 Pro chip

MacBook Pro (14-inch, 2023) and MacBook Pro (16-inch, 2023) models with the M2 Pro chip support up to two external displays simultaneously, based on the resolution (up to 8K) and refresh rate (up to 240Hz) of each external display.


One external display

Supports one display in any one of these configurations:

      • One display up to 6K at 60Hz over Thunderbolt
      • One display up to 8K at 60Hz (or 4K at 240Hz) over HDMI


Two external displays

Supports two displays in any one of these configurations:

      • Two displays up to 6K at 60Hz over Thunderbolt
      • One display up to 6K at 60Hz over Thunderbolt, and one display up to 4K at 144Hz over HDMI

 


MacBook Pro (2023) models with M2 Max chip

MacBook Pro (14-inch, 2023) and MacBook Pro (16-inch, 2023) models with the M2 Max chip support up to four external displays simultaneously, based on the resolution (up to 8K) and refresh rate (up to 240Hz) of each external display.


One external display

Supports one external display in any one of these configurations:

      • One display up to 6K at 60Hz over Thunderbolt
      • One display up to 8K at 60Hz (or 4K at 240Hz) over HDMI


Two external displays

Supports two external displays in any one of these configurations:

      • Two displays up to 6K at 60Hz over Thunderbolt
      • One display up to 6K at 60Hz over Thunderbolt, and one display up to 8K at 60Hz (or 4K at 240Hz) over HDMI


Three external displays

Supports three external displays in any one of these configurations:

      • Three displays up to 6K at 60Hz over Thunderbolt
      • Two displays up to 6K at 60Hz over Thunderbolt, and one display up to 8K at 60Hz (or 4K at 240Hz) over HDMI


Four external displays

Supports four external displays in this configuration:

      • Three displays up to 6K at 60Hz over Thunderbolt, and one display up to 4K at 144Hz over HDMI."



This is explained here: How many displays can be connected to MacBook Pro - Apple Support. We hope this helps. Let us know if we can assist with anything else at all. Take care.



Aug 25, 2023 1:57 PM in response to Gena_D

If the OP is using a 14" or 16" MacBook Pro with a M2 Pro or M2 Max chip, then according to the information that you posted, it should support at least two 4K displays running at a refresh rate of 60 Hz each.


The problem he is reporting is that he can only get one of the two displays to run in "like 2560x1440" mode. I am currently using a Mac running Ventura with a 4K monitor, and Displays Settings shows five choices.


Using System Information (Option– / System Information…) > Graphics and Displays, I see that the option on the far left ("Larger Text") maps to "Resolution: 3840 x 2160 (2160p/4K UHD 1 - Ultra High Definition) / UI Looks like: 1920 x 1080 @ 60.00Hz"


The one next to it maps to "Resolution: 5120 x 2880 (5K/UHD+ - Ultra High Definition Plus) / UI Looks like: 2560 x 1440 @ 60.00Hz". (But it's still a 4K monitor, so the hardware downscales the internal drawing canvas to 4K – to make the content fit the screen.)


The one on the far right selects native resolution (3840 x 2160) with no Retina UI scaling.


The OP is saying that he wants to run both of his 4K / 60 Hz monitors at the "UI Looks like: 2560 x 1440 @ 60 Hz" setting – but that his MacBook Pro will not let him do this. It will only let him run one monitor at that setting – the other gets forced to use "UI Looks like: 1920 x 1080 @ 60.00 Hz" or to use native resolution with no scaling.


I don't see anything in the specifications for the 14" and 16" M2 (Pro/Max) MBPs about such a restriction.


Note that the 13" M2 MacBook Pro only supports a single external display. So if that is the MBP that the OP has, the answer to "Why doesn't it allow selecting 'looks like 2560 x 1440' on both displays?" would be that that MBP does not support the use of two external displays.

Dual 4K setup cannot downscale

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