M1 Pro Dual Monitors 49" 5120x1440 Setup

[tdang]

Is anyone running a dual 49" monitors @ 5120x1440 setup?

I am getting the CalDigit Element Hub and looking to run both monitors with two usb c to DisplayPort 1.4 cables for 5120x1440 (120hz). Any suggestions or feedback regarding this setup?

 

[omnimax]

I suspect that a single TBT3 port won't have enough bandwidth to support 2x of those displays @120hz and you may need 2 of those hubs.

 

[tdang]

The element hub has 3 thunderbolt ports.. but you're saying that the dock will not be able to power two ports at 120hz 5120x1440?

 

[lixuelai]

You don't have enough bandwidth between the hub and macbook. Not going to work at 120hz.

 

[tdang]

You don't have enough bandwidth between the hub and macbook. Not going to work at 120hz.

What are my options if I am to run both monitors at 120hz? Run the element hub with a CalDigit TS3?
Or should I run both monitors at 60hz?

 

[omnimax]

If you want to run 2x 5k/1440@120hz, you’ll need a solution that uses 2 tbt ports from the Mac; basically 1 display per port. You may be able to drive both displays @60hz thru 1 port connected to the hub.

 

[tdang]

If you want to run 2x 5k/1440@120hz, you’ll need a solution that uses 2 tbt ports from the Mac; basically 1 display per port. You may be able to drive both displays @60hz thru 1 port connected to the hub.

Meaning I can run two hubs as you previously suggested and power 1 display per hub? Fyi thank you!

 

[lixuelai]

I think you can get up to ~75hz but will need to use something like SwitchResX (maybe more if you reduce the chroma etc). Not guaranteed to work though but might as well try it. No point getting two docks, just connect 1 display directly to the MBP if you must have 120hz.

 

[joevt]

5120x1440 120Hz is 966MHz using CVT-RB timing.
That's like one 5120x2880 60Hz displays.
966MHz * 24bpp = 23Gbps.
But Thunderbolt is only 40 Gbps.
So you cannot connect two of those to the same Thunderbolt port unless you can reduce the bpp using DSC or 4:2:0. The displays probably don't support 4:2:0 (and it wouldn't look nice anyway) so DSC would be the way to go (only if your GPU supports DSC and the OS allows it).

Now, you could add a DisplayPort 1.4 MST Hub to each display. Mac OS doesn't support multiple displays using MST, but it can use a MST Hub to convert DisplayPort signals. A DisplayPort 1.4 MST Hub could take a HBR2 + DSC (12bpp) signal and convert it to HBR3 30bpp for the display.

However, macOS probably isn't smart enough to let you connect two DisplayPort 1.4 MST hubs at HBR2 link rate - it would probably connect one at HBR3 and the second at HBR.
HBR can do 966MHz only if DSC is set to 8bpp instead of 12bpp. I don't think macOS attempts DSC at any mode other than 12bpp.
But macOS might not choose to use DSC at all.

Two displays to a Thunderbolt port won't work if macOS sets one to use HBR3 and the other to use HBR.

On Intel Macs, I would use AGDCDiagnose to check the display link rates (HBR, HBR2, HBR3) and DSC status. I don't know how to do that on M1 Macs.
On Intel Macs, I would use WhateverGreen/Lilu to patch some GPU stuff (though currently it can't patch CoreDisplay framework in user space). I don't think anyone's looked at patching M1 Mac stuff.

An old Thunderbolt dock like the CalDigit TS3+ only supports HBR2 max link rate. I don't know if that output would support DisplayPort 1.4 MST Hub DSC input.

 

[tdang]

I’ll try running both on 60hz using one hub and usb c to dp 1.4 cables. 60hz is good enough for what I want to do.

 

[jasonmvp]

Sorry to necro this thread but: has anyone tried to drive a 4K/60 HDR display off of one of the CalDigit Element's Thunderbolt ports? Using a Type C to DisplayPort cable, specifically? I know direct to the laptop, 4K/60 HDR will work as I'm doing it with my older 2019 Macbook Pro. But the CalDigit TS3 can not support HDR through any of its on-board ports. Curious if the Element can; the CalDigit support folks weren't sure.

 

[joevt]

Sorry to necro this thread but: has anyone tried to drive a 4K/60 HDR display off of one of the CalDigit Element's Thunderbolt ports? Using a Type C to DisplayPort cable, specifically? I know direct to the laptop, 4K/60 HDR will work as I'm doing it with my older 2019 Macbook Pro. But the CalDigit TS3 can not support HDR through any of its on-board ports. Curious if the Element can; the CalDigit support folks weren't sure.

The CalDigit Element Hub has Goshen Ridge Thunderbolt controller which supports DisplayPort 1.4 which should support HDR.

The CalDigit TS3+ has Alpine Ridge Thunderbolt controller which is limited to DisplayPort 1.2 but macOS should enable HDR anyway (at least it does with a similar OWC Thunderbolt 3 dock with Alpine Ridge connected to Thunderbolt port of Mac mini 2018 which has Intel GPU).

 

[joevt]

I don't think macOS attempts DSC at any mode other than 12bpp.

Actually, there may be a preference to change the DSC target BPP but I haven't tried it.
https://forums.macrumors.com/thread...-on-mac-pro-yes-you-can.2309750/post-30748427

 

[jasonmvp]

The CalDigit Element Hub has Goshen Ridge Thunderbolt controller which supports DisplayPort 1.4 which should support HDR.

The CalDigit TS3+ has Alpine Ridge Thunderbolt controller which is limited to DisplayPort 1.2 but macOS should enable HDR anyway (at least it does with a similar OWC Thunderbolt 3 dock with Alpine Ridge connected to Thunderbolt port of Mac mini 2018 which has Intel GPU).

I've got three TS3+ docks here, and have tried it with multiple variations of adapters, cables, etc. Nothing. I just can't get it to work until I bypass the dock and run the cable directly to the Macbook.

 

[joevt]

I've got three TS3+ docks here, and have tried it with multiple variations of adapters, cables, etc. Nothing. I just can't get it to work until I bypass the dock and run the cable directly to the Macbook.

Which MacBook and adapters? What GPU? For each adapter/cable, provide output from AGDCDiagnose. This will show info about the connection to the display and info about thee display. zip the results. Provide the output from the AllRez command as well. It will list all the modes and other info about your graphics.
https://forums.macrumors.com/thread...-on-mac-pro-yes-you-can.2309750/post-30760662

 

[jasonmvp]

Which MacBook and adapters? What GPU? For each adapter/cable, provide output from AGDCDiagnose.

My apologies. I actually did just get it working with the TS3+ using a USB-C to DP cable. What I was trying previously were straight DP cables since the TS3+ has that port. Didn't work. But connecting a USB-C to DP cable up to the Thunderbolt-3 port did the trick (I was using that previously for my 10GigE connection).

The Element also handles the same sort of thing since I have two HDR displays here. It's connected to both of them and I'm getting HDR on both. Cool.

 

[joevt]

My apologies. I actually did just get it working with the TS3+ using a USB-C to DP cable. What I was trying previously were straight DP cables since the TS3+ has that port. Didn't work. But connecting a USB-C to DP cable up to the Thunderbolt-3 port did the trick (I was using that previously for my 10GigE connection).

So the DisplayPort connector of your TS3+ is broken or you have a bad DisplayPort cable since the DisplayPort and Thunderbolt port of the TS3+ should have exactly the same capabilities for DisplayPort.

 

[jasonmvp]

So the DisplayPort connector of your TS3+ is broken or you have a bad DisplayPort cable since the DisplayPort and Thunderbolt port of the TS3+ should have exactly the same capabilities for DisplayPort.

That doesn't seem to be the case. I did try multiple cables, and I've got three TS3+ units here. None of them seemed to want to deliver HDR to the display; the laptop just never recognized the display as HDR-capable.

 

[najd]

My apologies. I actually did just get it working with the TS3+ using a USB-C to DP cable. What I was trying previously were straight DP cables since the TS3+ has that port. Didn't work. But connecting a USB-C to DP cable up to the Thunderbolt-3 port did the trick (I was using that previously for my 10GigE connection).

The Element also handles the same sort of thing since I have two HDR displays here. It's connected to both of them and I'm getting HDR on both. Cool.

So, you mean it’s possible to connect two HDR displays from an M1 Pro/Max using one TB cable passing the Element hub? If true, what resolutions and what refresh rates?

Thanks!

 

[joevt]

That doesn't seem to be the case. I did try multiple cables, and I've got three TS3+ units here. None of them seemed to want to deliver HDR to the display; the laptop just never recognized the display as HDR-capable.

But the display is recognized as HDR when connected to the Thunderbolt port instead of the DisplayPort port?

Which MacBook, adapters/cables, and GPU are you using?

 

[jasonmvp]

But the display is recognized as HDR when connected to the Thunderbolt port instead of the DisplayPort port?

Which MacBook, adapters/cables, and GPU are you using?

That's correct. Look in the signature for the hardware. As for the cables: I've lost track of which DP-to-DP cables I was using. Again: I have a pile of them because I use DP exclusively for my PC.

 

[jasonmvp]

So, you mean it’s possible to connect two HDR displays from an M1 Pro/Max using one TB cable passing the Element hub? If true, what resolutions and what refresh rates?

I'd be surprised if the M1 Pro/Max laptops were worse than what I'm getting, but I don't have one of those yet. Some day. Maybe. Whenever Apple ships it. I'm not holding my breath. The laptop I'm testing this all on is in my signature, and yes: I'm driving two 4K/60 HDR displays through the single Thunderbolt connection via the Element.

 

[nlr]

Has anyone got this working? I asked a similar question here:

dual 49WQ95C-W (Mac Mini or Studio) | MacRumors Forums

I would really appreciate some advice before buying everything

Thanks