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I just got an M1 mini so can add a little more to the discussion.

Parts:
M1 Mini
LG C1
Asus PG32UQX
Club 3D CAC-1567
Club 3D CAC-1085
Cable Matters 201388-GRY

LG C1
Cable Matters - 4k 60Hz HDR, 1440p 120 Hz, No VRR
2x C3D - 4k 60Hz HDR (it was janky, took a few reboots to even work)

PG32UQX
Club 3D CAC-1567 - 4k 144 Hz, VRR, HDR

So, still backs up everything so far, the hardware can do it just not with HDMI
 
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I am going to try this with my m1 Max - https://www.amazon.com/dp/B09J2F57VV?psc=1&smid=A3N79S5HNMK5S4&ref_=chk_typ_imgToDp

with DP coupler connected to the Club 3D CAC-1085 to my Bravia 4k 120 FPS monitor. I will report back with results when it all comes in, unless someone smarter than I have already tried this and can spare me the trouble?
It won't work. It's the same as a direct USB-C to HDMI 2.1 adapter. The USB-C to DisplayPort 1.4 cable is just Alt mode.

yea, i agree. the expensive m1 ultra product (with hdmi2.0) hints that, at least before m2 series come, there seems to be no hope ...
It's not a hardware issue but software. There's no need for a HDMI 2.1 port to fix this right now.
 
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It won't work. It's the same as a direct USB-C to HDMI 2.1 adapter. The USB-C to DisplayPort 1.4 cable is just Alt mode.


It's not a hardware issue but software. There's no need for a HDMI 2.1 port to fix this right now.
I guess the point is, if there has no official product with HDMI 2.1( Mac with HDMI 2.1 port or HDMI 2.1 Adapter) , Apple will not fix this problem.
 
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It won't work. It's the same as a direct USB-C to HDMI 2.1 adapter. The USB-C to DisplayPort 1.4 cable is just Alt mode.


It's not a hardware issue but software. There's no need for a HDMI 2.1 port to fix this right now.
yes, i agree. well, for most cases, apple only upgrades the software when there are outcoming products
 
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It won't work. It's the same as a direct USB-C to HDMI 2.1 adapter. The USB-C to DisplayPort 1.4 cable is just Alt mode.


It's not a hardware issue but software. There's no need for a HDMI 2.1 port to fix this right now.
You were correct, I figured I would give it a go, very disappointing indeed.
 
I guess the point is, if there has no official product with HDMI 2.1( Mac with HDMI 2.1 port or HDMI 2.1 Adapter) , Apple will not fix this problem.
But the problem has nothing specific to do with HDMI 2.1.

You can do 4K @ 120Hz via HDMI 2.0 on a Mac when booted into Windows.
 
But the problem has nothing specific to do with HDMI 2.1.

You can do 4K @ 120Hz via HDMI 2.0 on a Mac when booted into Windows.
It's not the same problem. Windows can do 4k120 via HDMI 2.0 is because you can manually choose the color format to YUV 4:2:0. On the Mac platform, the problem is, whenever macOS detected the display device is using HDMI, it will limit the pixel clock frequency.

So when you plug in a c to HDMI 2.1 adapter, macOS will limit the frequency(bandwidth) to HDMI 2.0, and that's why macOS can not do 4k120(RGB). Furthermore, you can not choose YUV 4:2:0 format on macOS, so you won't be able to output 4k120 on macOS

(Sorry for my poor English
 
Just submitted my feedback request to Apple too. I've got a brand new M1 Ultra Mac Studio and an LG C2 OLED display, which looks fantastic unless I move anything, when it's stuck to 60Hz. That'd be fine if I wasn't being spoilt by 120hz when it's connected to my Windows computer! Really odd that they went with HDMI 2.0 in the first place but even more weird that they're artificially limiting Thunderbolt->HDMI 2.1 adapters to HDMI 2.0 speeds.
 
Just submitted my feedback request to Apple too. I've got a brand new M1 Ultra Mac Studio and an LG C2 OLED display, which looks fantastic unless I move anything, when it's stuck to 60Hz. That'd be fine if I wasn't being spoilt by 120hz when it's connected to my Windows computer! Really odd that they went with HDMI 2.0 in the first place but even more weird that they're artificially limiting Thunderbolt->HDMI 2.1 adapters to HDMI 2.0 speeds.
I've been following this thread for some time now but I registered just to ask you something. As far as I know, the LG C2 does have DSC, so is there any options in the C2 to enable DSC?
 
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I've been following this thread for some time now but I registered just to ask you something. As far as I know, the LG C2 does have DSC, so is there any options in the C2 to enable DSC?
Interesting. I've gone through the settings on the C2 and I can't find any option to turn on DSC so maybe it's just on by default. I could maybe buy a thunderbolt->HDMI 2.1 adapter to test though but I was planning on saving my money until a DP 1.4->HDMI 2.1 adapter came out.
 
Interesting. I've gone through the settings on the C2 and I can't find any option to turn on DSC so maybe it's just on by default. I could maybe buy a thunderbolt->HDMI 2.1 adapter to test though but I was planning on saving my money until a DP 1.4->HDMI 2.1 adapter came out.
You should get one. You can always return it.

Edit: If the image they have actually contain the Realtek RTD2173, then this adapter is actually a DP 1.4 to HDMI 2.1.
 
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Sigh* there goes my C2 buying plan. I guess my only option is the Alienware QD-OLED or the Aorus Monitor (based on CX).
I mean, it's a *gorgeous* monitor. I imagine within 6 months or so, there'll probably be an actual PC monitor with display port, so you could wait for that! :D
 
I mean, it's a *gorgeous* monitor. I imagine within 6 months or so, there'll probably be an actual PC monitor with display port, so you could wait for that! :D
I actually have the CX, and was thinking of upgrading to C2 lol. But yeah I'm sure eventually there will be an Aorus equivalent of the C2.
 
Another confirmation here that we can’t get anything above 4K@60hz over HDMI. My setup is a QN800A 8K TV, 14” M1 Pro MackBook Pro, Club3D USB-C to HDMI 2.1 adapter (CAC-1586), Zeskit 8K HDMI cable (tested to work). No 4K@120hz or 8K@60hz, and can’t make any custom resolutions/timings in SwitchResX.
 
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Another confirmation here that we can’t get anything above 4K@60hz over HDMI. My setup is a QN800A 8K TV, 14” M1 Pro MackBook Pro, Club3D USB-C to HDMI 2.1 adapter (CAC-1586), Zeskit 8K HDMI cable (tested to work). No 4K@120hz or 8K@60hz, and can’t make any custom resolutions/timings in SwitchResX.
Yeah, the M1 display engine cannot output 8K.
 
I'm wondering if this device might be a solution.


This device only supports SST on MacOS, which means all three outputs show the same thing. This is exactly what we need though.

The idea here:

-macOS sees this splitter, which probably passes through the EDID of ONE of the monitors on the split output. You plug a EDID emulator or a broken 144Hz 4K monitor board in first.

-Then you plug in the DP1.4 to HDMI 2.1 adapter into this splitter. macOS mirrors the signal to this one. It doesn't see the EDID, which supposedly is the problem.

Anyone who would want to try this would need a Mac M1, a USB C to DP, a DP cable to this splitter, a 4K 144Hz displayport device, and a DP1.4 to HDMI2.1 adapter, and a HDMI2.1 TV or monitor.
 
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