What is required in order to run dual 4K @ 120Hz monitors on Macbook Pro M4?

What is required in order to run dual 4k monitors at 120hz on a Macbook M4 Pro? Apple says it can handle that but I have yet to figure out a way to do it. I have two macbook m4 pro laptops (13"/15") and I have not been successful with either one.

I have tested various different connectors at this point. Such as USB C to HDMI 2.1 connectors that have the driver flashed to work, HDMI 2.1 to USB C cables, powered USB-C to HDMI 2.1.

I can't get both displays to get signal at the same time. Each one works individually at 4k @ 120hz but two of them won't work together which means its a throughput issue. But the M4 pro is supposed to be able to handle 4k @ 120hz just fine.

USB-C To HDMI (Monitor 1)

Macbook PRO HDMI Port to HDMI 2.1 (Monitor 2)

Posted on Dec 15, 2025 9:54 AM

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19 replies

lkrupp

Level 7

27,449 points

Dec 15, 2025 12:11 PM in response to Macbook_Pro101

Macbook_Pro101 wrote:

So there is no way to achieve 4k 120 HZ across two displays on a Macbook Pro M4 Pro at all?

Nope. Why did you think you could? Just assumed?

Dec 16, 2025 9:09 PM in response to lkrupp

How many displays can be connected to MacBook Pro - Apple Support

I was reading this page and it says Macbook Pro M4 and M4 Pro can handle

Two displays up to a native resolution of 6K (6144 x 3456) at 60Hz or 4K (3840 x 2160) at 144Hz over Thunderbolt or HDMI

Dec 16, 2025 9:44 PM in response to Macbook_Pro101

Thanks for providing a reference. That is more than Technical Specifications promise.

I wonder if the higher refresh rate might be conditional on the connection being a Thunderbolt one, or perhaps a USB-C ( DisplayPort Alt Mode v2.1 ) one. If your monitors or adapters do not support these standards, perhaps you do not get the increased refresh rate.

Dec 17, 2025 9:49 AM in response to Macbook_Pro101

<< 4K (3840 x 2160) at 144Hz over Thunderbolt or HDMI. >>

USB-C data rates are capped at the maximum speed of USB-C, which is 20 G Bits/sec and falls far short of what is required to support a 4K display at much higher than 60 Hz.

DIRECT HDMI port in M2 Pro and later can run HDMI 2.1 speeds supporting 4K at up to 240 Hz.

ThunderBolt-to-HDMI does not work, partly because HDMI demands 42 G bits/sec, and Thunderbolt -3 or -4 supports 40 G bits/sec Max. Also because the adapter would get really hot and be unreliable.

ThunderBolt-direct or ThunderBolt-to-DisplayPort 1.4 would work, but I have never seen and freestanding dongles, only Docking stations that can output DisplayPort 1.4, which includes data rates of HBR3 25.92 G bits/sec, high enough for 4K at 120 Hz uncompressed and HDR=OFF. That might require Display Stream Compression (DSC) to reach 144 Hz.

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What is required in order to run dual 4K @ 120Hz monitors on Macbook Pro M4?