DP/USB-C/Thunderbolt to HDMI 2.1 4k@120hz RGB4:4:4 10b HDR with Apple Silicon M1-M4 now possible !

[Cappu]

Finally getting my first ever Mac – a brand-new Mac Studio! 🎉 Went for the M4 Max (64GB RAM / 1TB SSD), plus an extra 4TB SSD in a Thunderbolt 5 enclosure. The Ultra felt like overkill for my needs.

Right now, I’m using an LG OLED 42C26LB as my monitor on my PC. Would this still be a good option, even though the PPI isn’t as sharp as something like the Apple Studio Display? Also, what’s the best way to connect the LG C2 OLED to the Mac Studio via TB5 for the highest possible image quality?
Are there any wake-up issues when using this setup with macOS? And how does volume control work on a Mac with an external OLED like this?

Would love to hear some insights!

 

[Cupertony]

I’ve been experiencing intermittent screen blackouts every 20 seconds for the past few days. The display flickers, turns off for a second, and then comes back on.

I’m using a MacBook Pro M1 Max (Sequoia 15.3.1) connected to an LG C3 with the CableMatters cable.

I’ve tried using a different MacBook Pro, different ports, and various settings in BetterDisplay, but the issue persists no matter what.

Could it be the cable, or is anyone else experiencing this on 15.3.1?

 

[awer25]

Finally getting my first ever Mac – a brand-new Mac Studio! 🎉 Went for the M4 Max (64GB RAM / 1TB SSD), plus an extra 4TB SSD in a Thunderbolt 5 enclosure. The Ultra felt like overkill for my needs.

Right now, I’m using an LG OLED 42C26LB as my monitor on my PC. Would this still be a good option, even though the PPI isn’t as sharp as something like the Apple Studio Display? Also, what’s the best way to connect the LG C2 OLED to the Mac Studio via TB5 for the highest possible image quality?
Are there any wake-up issues when using this setup with macOS? And how does volume control work on a Mac with an external OLED like this?

Would love to hear some insights!

You’re one of the first to try, but for a C2 I believe HDMI is easiest and should support up to 4K@240Hz (C2 does 120Hz) with a good HDMI 2.1 cable.

 

[qxp]

Since I updated to MacOS Sequoia I noticed I lost HiDPi under 4k 120hz 10bit
At first I thought, ok I will be patiently waiting for update fix, BetterDisplay and MacOS updates seems not fixed anything related to it in the meantime, so finally found a time and tryed something and fixed it my way

My Setup:

MacBook Pro M1 | Sequoia 15.3.1
LG TV OLED C3 42" | Gaming mode enabled
CableMatters USB C to HDMI 2.1 with flashed firmware 7.02.112
(link for download from CM: https://cablematters.wetransfer.com/downloads/ef1e952e21aafc8b785aeef1bcedf29e20230804190846/5a41ac )
BetterDisplay Pro

So here is my hotfix with BetterDisplay settings:


1. Switch to 4K 60Hz

2. Enable HiDPi

3. Colour mode: 10bit RGB full

4. Go to Configuration Protection section, select Resolution and Colour Mode


5. Refresh Rate - select 120Hz (at first it only showed me 119.88Hz but LG menu says its 120Hz anyway, go with that and if unhappy repeat), if you still lack 120Hz or 119.88Hz option try change Colour Mode to 10bit 444 and later repeat process with 10bit RGB

6. Configuration Protection select Refresh Rate



I hope it helps someone



Btw, why that HDR issues is not fixed in Sequoia? I mean playing ytb videos with HDR are totally washed off with HDR enabled

 

[CallMeMorgana]

Still waiting for the M4 Macs to support 1440p HiDPi 240hz HDR on 4k panels...

 

[so_it_goes]

Is anyone else experiencing dramatic frame rate drops when using any video streaming sites (Youtube, Twitch, Live TV streams). The frame rate drops gets worse when you enter full-screen view on any video streaming site to the point where it's unwatchable.

Not sure if this happened since updating to Sequoia 15.3.2 (24D81) but I can't watch anything in full screen now without the stream quality moving at like 5 FPS.

Forgot to add, I'm using the pre-flashed Cable Matters 48Gbps USB C to HDMI 2.1 Adapter for macOS from my M2 Macbook Air. It's not a RAM (24GB) or and SSD (1TB) issue. 120hz is still working on my external monitor, but when I watch any video content via streaming platforms in full-screen, the frame rate is awful.

 

[komuh]

Is anyone else experiencing dramatic frame rate drops when using any video streaming sites (Youtube, Twitch, Live TV streams). The frame rate drops gets worse when you enter full-screen view on any video streaming site to the point where it's unwatchable.

Not sure if this happened since updating to Sequoia 15.3.2 (24D81) but I can't watch anything in full screen now without the stream quality moving at like 5 FPS.

Forgot to add, I'm using the pre-flashed Cable Matters 48Gbps USB C to HDMI 2.1 Adapter for macOS from my M2 Macbook Air. It's not a RAM (24GB) or and SSD (1TB) issue. 120hz is still working on my external monitor, but when I watch any video content via streaming platforms in full-screen, the frame rate is awful.

I got some frame freeze from time to time on Safari with youtube but it was also happening on all previous 15 system versions

 

[awer25]

Update on the Samsung G9 57" and M4 Max Mac Studio:

I've tried two different USB-C to DP 2.1 certified cables, and the max I can reach is the native 7680x2160@120Hz without HiDPI (HDMI 2.1 port still limited to 60Hz at native resolution). HiDPI seems locked to 3840x1080 and below, and 240Hz seems locked to 5120x1440 max so far. I'm not sure if this is a bandwidth limitation or MacOS limitation. G9 is set to DP2.1 and is on the latest 1007 firmware.

Using DP2.1, BetterDisplay also can't detect the DDC capabilities other than "DDC channel" whereas I thought it could before on my M1 Ultra Mac Studio.

I'd like to get HiDPI working at the native resolution, but haven't figured it out yet - even at 60Hz.

 

[kasakka]

Well guys, I'm trading in my M1 Ultra for an M4 Max Studio with HDMI 2.1 and DP 2.1. Looking forward to running the Samsung 57" G9 at its native resolution as a single 120Hz monitor (maybe even 240Hz). I'll update once it gets here.

You will be disappointed. Scaling maxes out at 3840x1080 which is IMO annoyingly large. The only sensible option is using Picture by Picture mode with two inputs.

Otherwise both DP 1.4 and HDMI 2.1 will run 7680x2160 @ 120 Hz just fine over a single input. It's the scaling that is the huge problem with this display.

MacOS is downright idiotic when it can run freaking 3x 4K 120 Hz displays with HiDPI scaling, but it cannot run one 8Kx2K over a single input without severely limiting scaling options.

The issue seems to be that MacOS limits HiDPI scaled resolution to a framebuffer of 7680x4320. But properly scaling levels for this display are all >10K horizontal res.

Of course, Windows has none of these issues because its scaling is more advanced.

There's honestly no proper recourse for this until Apple removes those limits. I don't think they will care when their 5K and 6K displays skirt under those limitations.

 

[awer25]

You will be disappointed. Scaling maxes out at 3840x1080 which is IMO annoyingly large. The only sensible option is using Picture by Picture mode with two inputs.

Otherwise both DP 1.4 and HDMI 2.1 will run 7680x2160 @ 120 Hz just fine over a single input. It's the scaling that is the huge problem with this display.

MacOS is downright idiotic when it can run freaking 3x 4K 120 Hz displays with HiDPI scaling, but it cannot run one 8Kx2K over a single input without severely limiting scaling options.

The issue seems to be that MacOS limits HiDPI scaled resolution to a framebuffer of 7680x4320. But properly scaling levels for this display are all >10K horizontal res.

Of course, Windows has none of these issues because its scaling is more advanced.

There's honestly no proper recourse for this until Apple removes those limits. I don't think they will care when their 5K and 6K displays skirt under those limitations.

Thank you for this info. I think I’ll go back to using two inputs, that way I should be able to get HiDPI and maybe 240Hz, plus as a single display, having the menu bar stretched across the whole monitor wasn’t as easy to use as when it was just on half.

 

[ultratiem]

5. Refresh Rate - select 120Hz (at first it only showed me 119.88Hz but LG menu says its 120Hz anyway, go with that and if unhappy repeat)

You SHOULD be running the C3 on 119.88. This controls flicker on video as the multiplier works off most media. The tiny loss doesn’t matter in gaming.

The rate is there to compensate for differences in frequencies as OLED has a zero refresh rate, it can be twitchy with content that demands an odd integer.

 

[kasakka]

Thank you for this info. I think I’ll go back to using two inputs, that way I should be able to get HiDPI and maybe 240Hz, plus as a single display, having the menu bar stretched across the whole monitor wasn’t as easy to use as when it was just on half.

The best setup on this display is 21:9 + 11:9 split. It does come with some weird caveats, again thanks to MacOS.

The 11:9 portion has to be connected via Displayport, or else you are limited to 60 Hz. It's like MacOS does not know what to do with a 2560x2160 resolution.

21:9 should be connected via HDMI 2 or 3 ports. HDMI 1 inexplicably only does 60 Hz, when it works fine at 120 Hz on Windows.

Then you can have HiDPI scaling and 120 Hz on both. PbP limits max refresh rate to 120 Hz on this display.

Finally you want to use BetterDisplay's Configuration protection features. Otherwise when waking from sleep it might try to go into mirroring mode, or do some other shenanigans. The DP side wakes up faster than the HDMI side. Why? Who knows.

Sometimes you will still encounter that MacOS shuffles your virtual desktops around, or the 21:9 side gets detected as 3440x1440. Using BetterDisplay's "Reinitialize external displays" feature fixes this.

2x 4K split seems to be a bit more stable.

MacOS is a complete piece of **** when it comes to external display handling.

 

[Zorast]

Any known problems with macOS 15.3.2 ?

 

[Zorast]

Since I updated to MacOS Sequoia I noticed I lost HiDPi under 4k 120hz 10bit
At first I thought, ok I will be patiently waiting for update fix, BetterDisplay and MacOS updates seems not fixed anything related to it in the meantime, so finally found a time and tryed something and fixed it my way

My Setup:

MacBook Pro M1 | Sequoia 15.3.1
LG TV OLED C3 42" | Gaming mode enabled
CableMatters USB C to HDMI 2.1 with flashed firmware 7.02.112
(link for download from CM: https://cablematters.wetransfer.com/downloads/ef1e952e21aafc8b785aeef1bcedf29e20230804190846/5a41ac )
BetterDisplay Pro

So here is my hotfix with BetterDisplay settings:


1. Switch to 4K 60Hz

2. Enable HiDPi

3. Colour mode: 10bit RGB full

4. Go to Configuration Protection section, select Resolution and Colour Mode
View attachment 2491737

5. Refresh Rate - select 120Hz (at first it only showed me 119.88Hz but LG menu says its 120Hz anyway, go with that and if unhappy repeat), if you still lack 120Hz or 119.88Hz option try change Colour Mode to 10bit 444 and later repeat process with 10bit RGB

6. Configuration Protection select Refresh Rate
View attachment 2491738


I hope it helps someone



Btw, why that HDR issues is not fixed in Sequoia? I mean playing ytb videos with HDR are totally washed off with HDR enabled

Plz read the OP, there is still a fix for that

 

[JeffNicholls97]

Hey guys, I cant for the life of me get 120hz 4K HiDPI

set up:
M1 Mac Mini
MSI MAG 321UP QD-OLED 31.5 Inch 4K UHD
Cable Matters 48Gbps USB C to HDMI 2.1 Adapter for macOS
Better Display

I have looked at all the work arounds and none seem to work, I have no option for 4K HiDPI at 60hz

Is there a video tutorial anywhere that will help, i just bought this monitor yesterday and just stuck in a rut at the min!

Thanks

 

[JeffNicholls97]

Hey guys, I cant for the life of me get 120hz 4K HiDPI

set up:
M1 Mac Mini
MSI MAG 321UP QD-OLED 31.5 Inch 4K UHD
Cable Matters 48Gbps USB C to HDMI 2.1 Adapter for macOS
Better Display

I have looked at all the work arounds and none seem to work, I have no option for 4K HiDPI at 60hz

Is there a video tutorial anywhere that will help, i just bought this monitor yesterday and just stuck in a rut at the min!

Thanks

I have bought the display port to usb c adapter from cable matters and a display port cable 1.4 see if that makes any difference! Will keep posted tomorrow when it arrives

 

[Zorast]

I have bought the display port to usb c adapter from cable matters and a display port cable 1.4 see if that makes any difference! Will keep posted tomorrow when it arrives

Plz read the OP u have to flash it.

 

[JeffNicholls97]

Plz read the OP u have to flash it.

Thought you didn’t have to flash it if you buy the Mac OS ready one with the firmware?

 

[Zorast]

@allhere macOS 15.3.2 is confirmed without any seen new problems from my side.

 

[Zorast]

Thought you didn’t have to flash it if you buy the Mac OS ready one with the firmware?

So then u have to write CM Support why it does not work. We dont know what firmware they use. u can check and report.

 

[JeffNicholls97]

So then u have to write CM Support why it does not work. We dont know what firmware they use. u can check and report.

Okay thank you, I’ll send them a message now see what they say! Thanks

 

[JeffNicholls97]

So then u have to write CM Support why it does not work. We dont know what firmware they use. u can check and report.

I also was not sure if it was a cable matters issue as I’m getting 4k 120hz, just not the HiDPI option with it

 

[dnvjmh313]

Hey guys, I cant for the life of me get 120hz 4K HiDPI

set up:
M1 Mac Mini
MSI MAG 321UP QD-OLED 31.5 Inch 4K UHD
Cable Matters 48Gbps USB C to HDMI 2.1 Adapter for macOS
Better Display

I have looked at all the work arounds and none seem to work, I have no option for 4K HiDPI at 60hz

Is there a video tutorial anywhere that will help, i just bought this monitor yesterday and just stuck in a rut at the min!

Thanks

Me too. The maximum resolution under HiDPI is 3072×1728, and I can’t achieve 4K 60Hz HiDPI. Have you solved it?

 

[JeffNicholls97]

Me too. The maximum resolution under HiDPI is 3072×1728, and I can’t achieve 4K 60Hz HiDPI. Have you solved it?

Hey mate, yeah I did some digging in the Better Display Discord and someone linked a github forum where the developer of Better Display said that any M series macs will only go to that resolution with HiDPI, on the pro and max series can get native 4K with HiDPI

 

[Zorast]

Did someone test macOS 15.4 ?