Thunderbolt 4 to HDMI 2.1, thru M1 Pro chip, works?

jdo_apple, that was not a helpful answer. He labored to ask politely and specifically, and you send him to a specs page for him to decode himself? What kind of service is that? Just answer his question.

As far as I can tell, based on the specs page you linked, the answer to his question is "no, m1 pro/max does not support refresh rates over 60hz." Which is a real shame.

If that's not the case, then please provide a better answer. The specs page gives no indication that the new MacBooks support anything higher than 60Hz refresh rate. Sorry ZenithJVM.

Hi,

On my Mac mini M1, I made several tests to try to put in 4k 120hz my oled TV that I use as a screen, but without success.

Even with a hdmi 2.1 to Type-c cable, MacOS blocks at 60hz, it's too annoying

Hello and welcome to Apple Support Communities, ZenithJVM.

If we understand your post correctly, you'd like to know more about the video support capabilities of the 14" MacBook Pro. We’d like to help.

Follow the steps in "Video Support" section of this page:

MacBook Pro 14" and 16" - Technical Specifications

Thanks for using the Apple Support Communities.

The Mac can send a signal fast enough over ThunderBolt or USB-C. Your adapter must be able to convert to HDMI 2.1, if that is what you need.

also, HDMI 2.1 requires special cables, tagged with anti-counterfeiting/ certification tags, that say :

"Ultra High Speed HDMI cable" or that + "48G"

According to the Specs page linked by the Community Specialist, the new MacBook chips do not support any external monitoring higher than 60Hz as far as I can tell. Sure, the Thunderbolt port can convert to HDMI 2.1 perhaps, but that won't support more than 60Hz, will it? Can you clarify your answer? Please correct me if I'm wrong, I hope you are right.

..lupus_custos:

Perhaps we may have to consider yours, an interjection.

An equivalent of "thread-jacking" ~ w/o Introduction?

The specifications are plenty; and maybe well beyond.

That said; those are great specs.. & Your Qualifications?

"ProMotion technology for adaptive refresh rates up to 120Hz

Fixed refresh rates: 47.95Hz, 48.00Hz, 50.00Hz, 59.94Hz, 60.00Hz"

~ just the tip of the iceberg. [2+ external displays, too]

Maybe you could let the thread author digest all those specs.

As for my interest? ~ As a 'Volunteer' here, my efforts are slim.

Apologies for the interruption.

zenithJVM: Pardon me..

..Carry on! 🌻🌿🌞🤖❄️

Unless I'm mistaken, the ProMotion tech (up to 120Hz) is in reference to the internal display of the MacBook Pro. However, if you go under the "Video Support" section, it says, "Up to two external displays with up to 6K resolution at 60Hz at over a billion colors (M1 Pro) or Up to three external displays with up to 6K resolution and one external display with up to 4K resolution at 60Hz at over a billion colors (M1 Max)."

The original question was in regards to external displays supporting 120Hz refresh rate. Seems to me the MacBook Pro does not support this. Am I wrong?

HDMI has substantially lower bandwidth than DisplayPort, DisplayPort encapsulated in USB-C, or DisplayPort encapsulated in ThunderBolt.

DisplayPort Dual-Mode (DP++), also called Dual-Mode DisplayPort, is a standard which allows DisplayPort sources to use simple passive adapters to connect to HDMI or DVI displays. 

[...]

With the release of the DisplayPort 1.3 standard, VESA added dual-mode support for up to a 600 MHz TMDS clock (18.00 Gbit/s bandwidth), the full bandwidth of HDMI 2.0. This is sufficient for 1920 × 1080 at 240 Hz, 2560 × 1440 at 144 Hz, or 3840 × 2160 at 60 Hz. However, no passive adapters capable of the 600 MHz dual-mode speed have been produced as of 2018.

from:

https://en.wikipedia.org/wiki/DisplayPort

Executive summary: You are going to need a more capable display with a DisplayPort input.

Here’s the most in depth discussion with possible solution from apple (if they choose to hear the users and fix it). Bottom line is there no physical limitation preventing a Mac mini M1 to drive a 4K @ 120hz display with a thunderbolt to hdmi adapter but it’s software limited. Please report this to apple as per the link if you want to see this resolved. https://forums.macrumors.com/threads/mac-mini-4k-120hz.2267035/page-10?post=30690647#post-30690647

This is true for HDMI 2.0, however, in order to support 10-bit HDR @ 8K/60hz or 4K/120hz, you would need HDMI 2.1, which was designed to use 48 Gbps bandwidth. Thunderbolt/USB-C only was designed to use 40, so you can't fully support HDMI 2.1.

However, you can still support 4K/120hz with USB-C to DP 1.4, which will run at 30 Gbps, it won't support 10 bit HDR though and likely will have chroma compression.

Mac also has a software limitation on USB-C to HDMI 2.1 cable, it'll only run at 4K/60hz even though the cable is fully capable of running 4K/120hz. Apple should fix this soon.

HDMI 2.1 is a not just a pedestrian evolution of the HDMI standard. It is a completely different standard than all that went before it. The clock signal is eliminated in favor of self-clocking data, and the former clock signal is repurposed as a data signal, and the switching speeds are increased so dramatically that the third-party DisplayPort-to-HDMI2.1 adapters are in metal enclosures with warnings they may routinely reach 160 degree F -- hot enough to burn your skin.

All of of these issues are because of choices made early on in HDMI. It was intended as a simple 5 Volt consumer standard for interfacing to TV sets, and it is still good for that. Pushing it so far that the adapter heats up to dangerous temperatures is not sensible.

Use DisplayPort -- at least it won't burn your skin off.

Why do you think these greedy people will fix it? The product has (M1 Macmini) has been out for more than a year and nobody has fixed anything. These people will not fix it.

Not 120Hz. Not 4:4:4 HDR 4k 60Hz even. Not through a USB C to HDMI 2.1 adapter that works perfectly on Windows. Not through a DP to HDMI 2.1 adapter either.

You know why? $$$. That is why. You better be saving up to buy the next model and hope that it works.

These are the people who released a brand new Apple TV with HDMI 2.1 but the software does not support FRL. So it is effectively running at HDMI 2.0 bandwidth. Sure the hardware is there but the software? It’s junk.