2 Monitor Setup with 5k Monitors and 120 hz

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Level 1

4 points

2 Monitor Setup with 5k Monitors and 120 hz

I have an Apple MacBook Pro M4 and I want to connect two Monitors. I have one Monitor with 5k Resolution at 120 hz and one 2.7k Monitor with 144 hz. I have tried different settings and different cable combinations.

Now I have the 5 k Monitor connected with a TB 4 cable provided by the Monitor manufacturer and the second one with a UGREEN 8k TB to Display Port cable, because this monitor only supports more then 60 hz only by Display Port.

Currently I only get both running wen I plug in the smaller one first and the the big one, but then the big one only works with 60 hz.

Do you have an idea how to get the 120 hz working?

PS: If I only connect the big one the 120 hz are working fine

MacBook Pro 14″, macOS 26.2

Posted on Feb 2, 2026 7:07 AM

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Answer 1

Feb 2, 2026 8:46 AM in response to JulianCCA

Both HDMI and DisplayPort (used inside Thunderbolt and USB-C) are packet interfaces. In each case, the interface runs at one of a few Fixed speeds, and if there is LESS data than fully fills every packet at that speed, then packets are (generally) omitted, or stuffed with null data.

You can not run combinations of resolution, bits/color, AND refresh rate that exceed the top speed of the pathway provided. If the display supports Display Stream Compression (DSC) you can get slightly higher data rates (seen as combinations of resolution, bits/color, and refresh rate).

In all cases, use of cables that are sub-standard or longer than allowed can cause the Mac to drop the connection. Comparing to performance under Windows is nonsense, because Windows does not check for errors in transmission.

For standard ThunderBolt cables, the cables MUST be certified and carry the ThunderBolt logo, and be no longer than 0.5 meters in length. ThunderBolt-5 cables are subject to the same restrictions, and provide no additional benefit unless ALL devices involved are genuine ThunderBolt-5 devices. if you need longer cables, much more expensive ACTIVE cables can be obtained (staring at US$125).

The cables "shipped in the box" by MANY display-makers (other than Apple itself) are often 'lowest bidder' cables tossed into the box at the last moment. They are often sub-standard or exceed the length requirement.

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Answer 2

Feb 2, 2026 2:14 PM in response to JulianCCA

When you say that you have a M4 MacBook Pro, which M4 chip is in that machine?

Is it a plain M4, a M4 Pro, or a M4 Max? Even the specifications for the M4 Max model do not promise the ability to run a 5K display at a refresh rate of 120 Hz.

If it is a plain M4, the machine=

"Simultaneously supports full native resolution on the built-in display at 1 billion colors and:

Up to two external displays with up to 6K resolution at 60Hz over Thunderbolt, or one external display with up to 6K resolution at 60Hz over Thunderbolt and one external display with up to 4K resolution at 144Hz over HDMI
One external display supported at 8K resolution at 60Hz or one external display at 4K resolution at 240Hz over HDMI"

MacBook Pro (14-inch, M4, 2024) - Tech Specs - Apple Support

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Answer 3

Feb 2, 2026 11:23 AM in response to JulianCCA

if you can respond with the make&model of your displays, Readers can elaborate about what resolutions, color depth, and refresh rates are possible for each display.

In every case, your cables must not be sub-standard or over the allowed length, or the display may drop out due to transmission errors.

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Answer 4

JulianCCA Author

Level 1

4 points

Feb 2, 2026 10:01 PM in response to Grant Bennet-Alder

Hi @Grant,

I have the following Model: Apple MacBook Pro 14", November 2024, Chip: Apple M4 Pro (12 core CPU), 48 GB RAM, 1 TB memory --> MacBook Pro (14-inch, M4 Pro or M4 Max, 2024) - Tech Specs - Apple Support

The Monitors I am using:

Dell U4025QW - 5k@120hz (https://www.dell.com/de-at/shop/geschwungener-dell-ultrasharp-40-thunderbolt-hub-monitor-u4025qw/apd/210-bmdv/monitore-und-monitorzubeh%C3%B6r)
Asus ROG SWIFT PG278QR - 2.7k@up to 165hz (https://rog.asus.com/de/monitors/27-to-31-5-inches/rog-swift-pg278qr-model/)

Cable:

Thunderbolt to Display Port: https://amzn.eu/d/03MCYrer

Just to clarify: If I just plug only one of the monitors in, they support full resultion and refresh rate (the 5k monitor supports 5k resultion with 120 hz over the provided Thunderbolt 4 cable delivered by the manufacturer, and the 2.7 k Monitor supports 2.7k resolution with 144 hz over the Thunderbolt to display port cable). But the combination of both is not working (both cables are directly plugged in in the MacBook).

So I thought it is maybe a limitation of the bus traffic and so I thought if I limit e.g. the refresh rate of the smaller one, than the big one will support full resolution and refresh rate.

Currently I got only one working setup by plugging in the smaller one first which then supports the full resolution and refresh rate and when I then plug in the big one but then this one only supports 60 hz at 5k. Conversely, the second monitor doesn't work at all.

Hope thats enough information.

Thanks in advance

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Answer 5

Feb 2, 2026 7:42 AM in response to JulianCCA

what make&model display(s) ?

what sort of work are you doing? Is 10 bits/color important to you or not?

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