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Can you daisy chain a 4K monitor to the Studio Display?

R

ronm99

macrumors 6502
Original poster
Jan 13, 2012
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I have a mac studio and a studio display on order that will arrive mid-April.

I was wondering if I will be able to drive a 4K monitor from one of the USB ports in the back of the studio display? It would love to be able to unplug the studio display from my studio mac, and connect it to my macbook and have both monitors switch at the same time. If I used a wired mouse / keyboard, it would kind of be like a KVM switch.

I realize not many people would want to do this, but my macbook is for work and is only used for work, and my mac studio is my personal computer. It would be nice to easily switch the computers that are driving the displays.
 
I have the same question because I actually unplug my MacBook when I go somewhere, but would love to only put one cable instead of two.
We might need a thunderbolt 4 dock though
 
The Studio Display only passes through USB. They are stuck at 3.1 Gen 2 (10Gb/s).

So, no you can't. Although I suppose you might be able to jury rig it by using a DisplayLink USB-C adapter. Then you'll have the Studio Display with a direct DisplayPort connection and a 4K with a laggy DisplayLink connection.

Thunderbolt 4 only has enough bandwidth for a single 5K@60hz display. From what I can tell Thunderbolt 4/USB 4 is limited to UHBR10 . So, as long as both screens are not HDR. It should technically be able to handle one 5K@60Hz and one 4K@60Hz. Maybe Apple limits it so people don't try two 5K display or a 5K with a 4K HDR display. Although Apple also has had a questionable history with MST.

UHBR10 38.69 Gbit/s, 4:4:4 Uncompressed RGB/Y'CbCr
5K@60Hz (non-HDR) 22.18 Gbit/s
4K@60hz (non-HDR) 12.54 Gbit/s
5K@60Hz (HDR) 27.72 Gbit/s
4K@60hz (HDR) 15.68 Gbit/s

I don't think they'll ever be able to go to UHBR 13.5 or 20. Since the USB connection is bi-directional. Splitting the 80Gbit/s to 40 up and 40 down. While a pure DisplayPort connection can send all 80 Gbit/s to the monitors. At least not until Thunderbolt 5.

Also for everyone complaining about no 5K@120hz. That's not possible with UHBR10. It would require around 57Gbit/s with HDR. Thus a regular DisplayPort connector, no Thunderbolt/USB combo.
 
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velocityg4 said:
The Studio Display only passes through USB. They are stuck at 3.1 Gen 2 (10Gb/s).

So, no you can't. Although I suppose you might be able to jury rig it by using a DisplayLink USB-C adapter. Then you'll have the Studio Display with a direct DisplayPort connection and a 4K with a laggy DisplayLink connection.

Thunderbolt 4 only has enough bandwidth for a single 5K@60hz display. From what I can tell Thunderbolt 4/USB 4 is limited to UHBR10 . So, as long as both screens are not HDR. It should technically be able to handle one 5K@60Hz and one 4K@60Hz. Maybe Apple limits it so people don't try two 5K display or a 5K with a 4K HDR display. Although Apple also has had a questionable history with MST.

UHBR10 38.69 Gbit/s, 4:4:4 Uncompressed RGB/Y'CbCr
5K@60Hz (non-HDR) 22.18 Gbit/s
4K@60hz (non-HDR) 12.54 Gbit/s
5K@60Hz (HDR) 27.72 Gbit/s
4K@60hz (HDR) 15.68 Gbit/s

I don't think they'll ever be able to go to UHBR 13.5 or 20. Since the USB connection is bi-directional. Splitting the 80Gbit/s to 40 up and 40 down. While a pure DisplayPort connection can send all 80 Gbit/s to the monitors. At least not until Thunderbolt 5.

Also for everyone complaining about no 5K@120hz. That's not possible with UHBR10. It would require around 57Gbit/s with HDR. Thus a regular DisplayPort connector, no Thunderbolt/USB combo.
Click to expand...
Thank you for the information! Disappointing, but not unexpected.

I am a computer engineer, and I still find USB-C confusing ... it is a nice connector, but the cables / ports support so many different standards.
 
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velocityg4 said:
The Studio Display only passes through USB. They are stuck at 3.1 Gen 2 (10Gb/s).

So, no you can't. Although I suppose you might be able to jury rig it by using a DisplayLink USB-C adapter. Then you'll have the Studio Display with a direct DisplayPort connection and a 4K with a laggy DisplayLink connection.

Thunderbolt 4 only has enough bandwidth for a single 5K@60hz display. From what I can tell Thunderbolt 4/USB 4 is limited to UHBR10 . So, as long as both screens are not HDR. It should technically be able to handle one 5K@60Hz and one 4K@60Hz. Maybe Apple limits it so people don't try two 5K display or a 5K with a 4K HDR display. Although Apple also has had a questionable history with MST.

UHBR10 38.69 Gbit/s, 4:4:4 Uncompressed RGB/Y'CbCr
5K@60Hz (non-HDR) 22.18 Gbit/s
4K@60hz (non-HDR) 12.54 Gbit/s
5K@60Hz (HDR) 27.72 Gbit/s
4K@60hz (HDR) 15.68 Gbit/s

I don't think they'll ever be able to go to UHBR 13.5 or 20. Since the USB connection is bi-directional. Splitting the 80Gbit/s to 40 up and 40 down. While a pure DisplayPort connection can send all 80 Gbit/s to the monitors. At least not until Thunderbolt 5.

Also for everyone complaining about no 5K@120hz. That's not possible with UHBR10. It would require around 57Gbit/s with HDR. Thus a regular DisplayPort connector, no Thunderbolt/USB combo.
Click to expand...
That might not be the full answer.
There is DSC (Display stream compression) and apple manages to compress the 6k XDRs in a way that you can run two of them on one Thunderbolt Port.
Now that we know that the Studio Display only has 5k resolution, there should be plenty of bandwidth to connect a 4K Display using DSC as welll.
 
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velocityg4 said:
The Studio Display only passes through USB. They are stuck at 3.1 Gen 2 (10Gb/s).

So, no you can't. Although I suppose you might be able to jury rig it by using a DisplayLink USB-C adapter. Then you'll have the Studio Display with a direct DisplayPort connection and a 4K with a laggy DisplayLink connection.

Thunderbolt 4 only has enough bandwidth for a single 5K@60hz display. From what I can tell Thunderbolt 4/USB 4 is limited to UHBR10 . So, as long as both screens are not HDR. It should technically be able to handle one 5K@60Hz and one 4K@60Hz. Maybe Apple limits it so people don't try two 5K display or a 5K with a 4K HDR display. Although Apple also has had a questionable history with MST.

UHBR10 38.69 Gbit/s, 4:4:4 Uncompressed RGB/Y'CbCr
5K@60Hz (non-HDR) 22.18 Gbit/s
4K@60hz (non-HDR) 12.54 Gbit/s
5K@60Hz (HDR) 27.72 Gbit/s
4K@60hz (HDR) 15.68 Gbit/s

I don't think they'll ever be able to go to UHBR 13.5 or 20. Since the USB connection is bi-directional. Splitting the 80Gbit/s to 40 up and 40 down. While a pure DisplayPort connection can send all 80 Gbit/s to the monitors. At least not until Thunderbolt 5.

Also for everyone complaining about no 5K@120hz. That's not possible with UHBR10. It would require around 57Gbit/s with HDR. Thus a regular DisplayPort connector, no Thunderbolt/USB combo.
Click to expand...
UHBR is a DisplayPort 2.0 mode. I don't know of anything that does DisplayPort 2.0 yet.

If the Studio Display uses DSC for 5K60, then you should be able to connect that and another display to a Thunderbolt 4 hub or dock. Or you can chain a Studio Display to a 4K Thunderbolt display.
 
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joevt said:
UHBR is a DisplayPort 2.0 mode. I don't know of anything that does DisplayPort 2.0 yet.

If the Studio Display uses DSC for 5K60, then you should be able to connect that and another display to a Thunderbolt 4 hub or dock. Or you can chain a Studio Display to a 4K Thunderbolt display.
Click to expand...
How do we know if DSC is available? I couldn’t find any detailed specs on this so far.
 
Quasselstripper said:
How do we know if DSC is available? I couldn’t find any detailed specs on this so far.
Click to expand...
We don't. Waiting for people to post AGDCDiagnose or AllRez output from an AMD GPU or Intel GPU that supports DSC.
Some of the supported devices (iPads) don't have Thunderbolt. DSC is the only way to get 5K60 10bpc without Thunderbolt dual tile connection. They either use HBR2+DSC for 10bpc or HBR3 without DSC for 8bpc or they are limited to 4K. We need info from all the connection types to know the full capabilities of the display. #8
 
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User should never daisy chain thunderbolt or any other display. Read the Apple support DOCS.
 
D49 said:
User should never daisy chain thunderbolt or any other display. Read the Apple support DOCS.
Click to expand...
A Thunderbolt display with 2 Thunderbolt ports can have another display daisy chained to the 2nd Thunderbolt port.
5K and 6K Thunderbolt displays only have one Thunderbolt port.
 
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I've read the docs but that was long ago technology which I think was over blown and not understood very well. Thunderbolt and thunderbolt 2 did not have the bandwidth to handle it reliably. You'll not read about that regarding the thunderbolt 3 or 4 Macs. To be functionally reliable all thunderbolt should be to a thunder bolt bus and its port. The exclusion would be a device such as a Cal Digit TS3+ thunderbolt Dock where the Dock should be connected to a Macs thunderbolt bus and its port . Then a 4k display or whatever the dock is rated by thunderbolt. This keeps the entire system whole and trouble free.
 
D49 said:
Read the Apple support DOCS.
Click to expand...
Name an Apple support document. Then we can discuss what it says.

D49 said:
Thunderbolt and thunderbolt 2 did not have the bandwidth to handle it reliably.
Click to expand...
The Apple Thunderbolt Display uses Thunderbolt 1. It has two Thunderbolt ports to allow connecting a second Apple Thunderbolt Display.

D49 said:
To be functionally reliable all thunderbolt should be to a thunder bolt bus and its port
Click to expand...
Translation required.

D49 said:
connected to a Macs thunderbolt bus and its port
Click to expand...
Yes, Thunderbolt devices are connected to Thunderbolt ports.

D49 said:
Then a 4k display or whatever the dock is rated by thunderbolt.
Click to expand...
A dock has two ports that can each have a 4K display connected to it. You can connect two displays to a single dock (except Thunderbolt 1 and Thunderbolt 2 docks - you need a separate Thunderbolt 1/2 dock per display).
 
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Quasselstripper said:
Does that mean it works on macOS as well?
Click to expand...
What do you mean by "it"? DSC has nothing to do with the Studio Display's inability to daisy-chain.

D49 said:
Thunderbolt and thunderbolt 2 did not have the bandwidth to handle it reliably.
Click to expand...
I have daisy-chained two 2560×1440 displays to a Thunderbolt 1 Mac using two daisy-chained Thunderbolt docks. It worked fine. It was even an officially supported configuration using two Apple Thunderbolt Displays.
 
Last edited:
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andrewj said:
How about connecting a less than 4K monitor to the Apple Studio Display? Has anyone tried that before?
Click to expand...
The Apple Studio display has only one Thunderbolt port for DisplayPort input. It doesn't have a second Thunderbolt port because the Apple Studio Display has a dual link SST mode for Macs that don't support DSC to allow 5K60 10bpc like the LG UltraFine 5K. The Thunderbolt controller in the Apple Studio Display has one DisplayPort output for one of the two DisplayPort connections required for dual link SST. The second Thunderbolt port is used for getting the second DisplayPort connection.

All the USB-C ports of the Apple Studio Display are only for USB. They cannot be used to connect a display unless you're using a DisplayLink adapter.
 
But would it be possible to use a USB-C to DisplayPort adapter to connect to a 4K or less than 4K monitor?
 
andrewj said:
But would it be possible to use a USB-C to DisplayPort adapter to connect to a 4K or less than 4K monitor?
Click to expand...
Only if it's a USB-C to DisplayPort adapter using DisplayLink. DisplayLink converts USB data to DisplayPort. The USB data comes from the Mac, not the GPU.

I said all the USB-C ports of the Apple Studio Display are only for USB which does not include USB-C DisplayPort Alt Mode. USB-C DisplayPort Alt Mode means the USB-C pins are transmitting a DisplayPort signal. Such Alt Modes are negotiated between the host and device. Thunderbolt is also a USB-C alt mode.
 
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joevt said:
Only if it's a USB-C to DisplayPort adapter using DisplayLink. DisplayLink converts USB data to DisplayPort. The USB data comes from the Mac, not the GPU.

I said all the USB-C ports of the Apple Studio Display are only for USB which does not include USB-C DisplayPort Alt Mode. USB-C DisplayPort Alt Mode means the USB-C pins are transmitting a DisplayPort signal. Such Alt Modes are negotiated between the host and device. Thunderbolt is also a USB-C alt mode.
Click to expand...
To follow up, I just tried connecting a 24" 1920 x 1080 monitor to the back of the Studio Display using a USB-C to DisplayPort cable, and no it does not work, as joevt indicates. (It's fine though connecting the 24" to the MBP directly, though this takes away from allure of "one cable" connection with the Studio Display.)
 
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