CalDigit Launches Element 5 Hub With Thunderbolt 5

[whitby]

Apple Silicon Mac mini with two Apple Studio Displays? They should not blank occasionally. That just means poor connection quality or noise.
They work because they each use a single DisplayPort HBR2 x4 connection with DSC.

You can force an LG UltraFine 5K to use a single HBR2 x4 connection but then it would be limited to 5K39 (with a custom timing added….

OK. Thank you for the clarification. My info on the Apple Studio is that it used a dual DisplayPort connection, so would not work. This does mean that when I use the LG Ultrafine 5K with the Apple Studio display it should work on a TB 5 single port, but it does not using the OWC Thunderbolt 5 hub. Each display works fine when connected to the Mini directly to two separate ports, but not via the port using exactly the same cables. So I do not think it is the cables or noise. It is the Hub.

BTW where did you get the info on the Apple Studio display? When I searched the results said it required dual DisplayPort connections.

Thanks for your help.

 

[joevt]

OK. Thank you for the clarification. My info on the Apple Studio is that it used a dual DisplayPort connection, so would not work.

It only use dual DisplayPort connection when the GPU does not support DSC (Intel Macs with older GPUs that are not Ice Lake CPU or Radeon 5000 or 6000 series). By default, it uses DSC because that takes less bandwidth from Thunderbolt.

This does mean that when I use the LG Ultrafine 5K with the Apple Studio display it should work on a TB 5 single port, but it does not using the OWC Thunderbolt 5 hub.

As has been mentioned a few times in this thread, Apple Silicon Macs provide only two DisplayPort connections per Thunderbolt port - even for Thunderbolt 5. You might be able to connect the Apple Studio display first, then connect the LG UltraFine 5K display second - in that case, the LG UltraFine 5K might connect with a single DisplayPort connection. Or you can try force a single DisplayPort connection by using a Thunderbolt 20 Gbps cable (i.e. a USB-C cable supported USB 3.x gen 2 speed). If it's a newer LG UltraFine 5K then a USB-C cable might connect as USB-C DisplayPort Alt Mode. With single DisplayPort connection, You'll be limited to 4K60 or you can add a custom timing of 5K39.

You need a PC to get 3 displays from a Thunderbolt 5 hub. But in that case, even a Thunderbolt 3/4 dock can support 3 displays if the dock includes a MST hub or you connect an MST hub to the dock.

Each display works fine when connected to the Mini directly to two separate ports, but not via the port using exactly the same cables. So I do not think it is the cables or noise. It is the Hub.

It could be a combination of anything.

BTW where did you get the info on the Apple Studio display? When I searched the results said it required dual DisplayPort connections.

People connect displays to an Intel Mac and then gather info about the connection and the display using AllRez or similar utilities. The EDID contains info about the dual tile modes and the single tile modes. DisplayPort DPCD info contains info about DSC support and MST hub info. The list of display modes contains info about timing, color format, range, DSC, chroma subsampling, etc that the Apple drivers have chosen for you.

 

[whitby]

As has been mentioned a few times in this thread, Apple Silicon Macs provide only two DisplayPort connections per Thunderbolt port - even for Thunderbolt 5. You might be able to connect the Apple Studio display first, then connect the LG UltraFine 5K display second - in that case, the LG UltraFine 5K might connect with a single DisplayPort connection. Or you can try force a single DisplayPort connection by using a Thunderbolt 20 Gbps cable (i.e. a USB-C cable supported USB 3.x gen 2 speed). If it's a newer LG UltraFine 5K then a USB-C cable might connect as USB-C DisplayPort Alt Mode. With single DisplayPort connection, You'll be limited to 4K60 or you can add a custom timing of 5K39.

Unfortunately I missed this point, but understand and thanks for pointing it out. Trying to force the LG Ultrafine into single DisplayPort mode does not seem worth while. All my interconnects are Thunderbolt 4 compatible (40 Gbps) so I am not expecting any limitations due to the interconnects. And they do work reliably when connected directly to a TB 5 port on Mini.

It could be a combination of anything.

I agree but I have no idea what.

People connect displays to an Intel Mac and then gather info about the connection and the display using AllRez or similar utilities. The EDID contains info about the dual tile modes and the single tile modes. DisplayPort DPCD info contains info about DSC support and MST hub info. The list of display modes contains info about timing, color format, range, DSC, chroma subsampling, etc that the Apple drivers have chosen for you.

I will download your utility from GitHub and see how the display interfaces are being configured by Apple.

I think the bottom line is I need to leave it as I have it configured at the moment with the LG 5K Ultrafine connected to the HUB with the TB 3 RAID array and the Apple Studio display connected directly to the Mini and hang the USB peripherals off that display's USB ports. The remaining Mini TB 5 is connected to a TB 5 SSD drive (6000 MBps) which I suspect uses all PCIe channels.

I also would add that is seems the idea idea that Thunderbolt is a unifying interface standard is full of limitations that have to be understood before you try and use it. E.g. I had no idea the LG Ultrafine used 2 DisplayPort connections to get it to 5K60 and did not realize that this would severely limit its use on Apple silicon which only supports 2 Display Port connections per port (thus, I think (correct me I I am wrong) not meeting the Thunderbolt 5 standards). The fact that you need to know this before you can connect displays to a Thunderbolt part is rather disappointing. I am a retired electronics and software engineer and, although familiar with what Thunderbolt was designed to achieve and how it achieved this, I was not familiar enough with the requirements in enough detail to make it work. Sadly you have had to educate me on the details for which I am grateful.

Very grateful for your information and patience dealing with my ignorance.

 

[DELLsFan]

I'll also second CalDigit. Every other hub I've owned has died in a year. Theirs is still going after 3 years. I'll get this one.

I'm intrigued. Do I need CalDigit in my life and under my M4 Mini? Do I really need those TB5 speeds? Asking for my wallet.

 

[PaulD-UK]

@whitby "I had no idea the LG Ultrafine used 2 DisplayPort connections to get it to 5K60..."

Two DP streams (in the TB3 cable) rather than connections (which only exist at chip level within the actual Apple silicon itself)...

Actually this fact has been unnoticed in plain sight since 2016, as it is:
a) the only reason the iMac 5K was able to exist (because it internally needed two DP streams worth of bandwidth), and
b) the reason that Target Display Mode was discontinued in late 2014, as there were no Macs in existence until about five years later (when DP 1.4 and Display Stream Compression arrived) that could have easily supplied the two streams in a single cable.

The LG 5K was designed around the TB3 two stream solution to the single cable problem., and allowed Apple to specify that all TB3 Macs were '5K capable'.
But that use case is now legacy, and to require forward-looking standards to still adhere to it is not Apple's way... 😀

 

[joevt]

I think the bottom line is I need to leave it as I have it configured at the moment with the LG 5K Ultrafine connected to the HUB with the TB 3 RAID array and the Apple Studio display connected directly to the Mini and hang the USB peripherals off that display's USB ports. The remaining Mini TB 5 is connected to a TB 5 SSD drive (6000 MBps) which I suspect uses all PCIe channels.

If you must connect a display to the Thunderbolt hub, then wouldn't it be better to connect the Apple Studio Display, since it uses much less bandwidth than the LG UltraFine 5K, and it uses only a single DisplayPort connection, so that you could, in the future, connect a second display to the hub.

I also would add that is seems the idea idea that Thunderbolt is a unifying interface standard is full of limitations that have to be understood before you try and use it. E.g. I had no idea the LG Ultrafine used 2 DisplayPort connections to get it to 5K60 and did not realize that this would severely limit its use on Apple silicon which only supports 2 Display Port connections per port (thus, I think (correct me I I am wrong) not meeting the Thunderbolt 5 standards).

The Thunderbolt 5 minimum standard is two single tile displays up to 4K60 or 6K.

The fact that you need to know this before you can connect displays to a Thunderbolt part is rather disappointing. I am a retired electronics and software engineer and, although familiar with what Thunderbolt was designed to achieve and how it achieved this, I was not familiar enough with the requirements in enough detail to make it work. Sadly you have had to educate me on the details for which I am grateful.

Apple's technical specs for Intel Macs always specified one fewer 5K displays than 4K displays.
They changed this for Apple Silicon Macs. An M1 Mac supports only one display from Thunderbolt, but that display can be dual tile 5K display because there's an extra DisplayPort connection allowed only for dual tile displays.

Two DP streams (in the TB3 cable) rather than connections (which only exist at chip level within the actual Apple silicon itself)...

Consider the opposite end of the cable, inside the display, the display's Thunderbolt controller must convert the two tunnelled DisplayPort streams from upstream Thunderbolt into real DisplayPort connections to the display's circuitry.

Actually this fact has been unnoticed in plain sight since 2016, as it is:
a) the only reason the iMac 5K was able to exist (because it internally needed two DP streams worth of bandwidth), and
b) the reason that Target Display Mode was discontinued in late 2014, as there were no Macs in existence until about five years later (when DP 1.4 and Display Stream Compression arrived) that could have easily supplied the two streams in a single cable.

I don't know that Target Display Mode is impossible for dual tile displays.
The Thunderbolt 1 iMacs have a Thunderbolt 1 host controller with two DisplayPort In Adapters plus a DisplayPort Out Adapter. Thunderbolt Target Display Mode sets up a cross domain path from the DisplayPort In Adapter of the Thunderbolt controller of the source Mac to the DisplayPort Out Adapter of the Thunderbolt 1 controller of the iMac. The DisplayPort connection of the iMac's display is switched from the iMac's GPU to the DisplayPort Out Adapter of the iMac's Thunderbolt 1 controller.

Given all that, why couldn't two DisplayPort paths be created from the DisplayPort In Adapters of the Thunderbolt controller of the source Mac to the DisplayPort Out Adapters of the Thunderbolt controller of a dock connected to another Mac?
Because DisplayPort cross domain paths only work when the destination is a Thunderbolt 1 controller?
Because the cross domain path cannot be deeper than the host controller of the second domain?
Because it would involve deconstructing the existing path to the DisplayPort Out Adapters?

Someone should try adding Target Display Mode to Linux. This probably requires using a software connection manager instead of the ICM (internal connection manager) of the Thunderbolt controllers.
https://docs.kernel.org/admin-guide/thunderbolt.html

 

[whitby]

If you must connect a display to the Thunderbolt hub, then wouldn't it be better to connect the Apple Studio Display, since it uses much less bandwidth than the LG UltraFine 5K, and it uses only a single DisplayPort connection, so that you could, in the future, connect a second display to the hub.

I thought about this, but I want the most reliable display to be connected directly to the Mini. By connecting the Apple Display directly to the Mini, I will generally always have a display as I no longer trust the Hub or the LG Display to work. There should be plenty of bandwidth to run the LG and the TB 2 RAID Array. They are the least needed of the peripherals. I am unlikely to be purchasing another Apple Studio display in the near future, they are far too expensive.

The Thunderbolt 5 minimum standard is two single tile displays up to 4K60 or 6K.


Apple's technical specs for Intel Macs always specified one fewer 5K displays than 4K displays.
They changed this for Apple Silicon Macs. An M1 Mac supports only one display from Thunderbolt, but that display can be dual tile 5K display because there's an extra DisplayPort connection allowed only for dual tile displays.

OK, yet another misunderstanding. They keep stacking up and I am somewhat upset that because a) The LG uses two DisplayPort streams (and not one) and b) Apple only have the ability to support 2 DisplayPort streams on TB 5 the configuration I have to use is a compromise to get a working system. My bad. It sort of works but which ever display is connected to the Hub blanks on a regular basis (does not happen when both are connected directly to the Mini). At least it is only one of them now. I believe the OWC Hub is faulty, at least I hope that is the case.

Again appreciate you spending the time to review and comment.

 

[PhoenixDown]

I would like to see a version of this with a 2.5G ethernet port. Is that unrealistic?

edit to add: I guess I could use their Connect 10G adapter which would take up a Thunderbolt 5 (?) slot?

 

[leicaman]

And why USB-A ports when all the shiny things now are made with USB-C.

I don't want them, but some people need a few slow ports for keyboards and mice that won't eat up bandwidth from the faster ports.

 

[leicaman]

I would like to see a version of this with a 2.5G ethernet port. Is that unrealistic?

edit to add: I guess I could use their Connect 10G adapter which would take up a Thunderbolt 5 (?) slot?

Not at all. The current TS-4 Dock has a 2.5 gigabit port. I would prefer 10 gigabit, because my QNap NAS and Mac Mini Pro both have 10 GbE.

I have their 10 GbE Thunderbolt adapter (SFP+) and it works really well, but it does get quite hot. OWC makes an RJ45 version, which I also have, and it works just as well.

 

[Jonas Danielsson]

Not at all. The current TS-4 Dock has a 2.5 gigabit port. I would prefer 10 gigabit, because my QNap NAS and Mac Mini Pro both have 10 GbE.

I have their 10 GbE Thunderbolt adapter (SFP+) and it works really well, but it does get quite hot. OWC makes an RJ45 version, which I also have, and it works just as well.

Yes 10GbE has been minimum for many years for all media production and I would more than see a hub with 10GbE network and 2-3 thunderbolt and 3 usb c ( could be slow for control panl , audio interface etc ) and of course good quality would be something everyone in any media company would buy

 

[Jonas Danielsson]

I would like to see a version of this with a 2.5G ethernet port. Is that unrealistic?

edit to add: I guess I could use their Connect 10G adapter which would take up a Thunderbolt 5 (?) slot?

The connect 10G hasn’t been I stock for 2-3 years and also the link not working so i would hope on that. Maybe then a owc or sonette 10GbE

 

[xpaulso]

Apple Silicon Mac mini with two Apple Studio Displays? They should not blank occasionally. That just means poor connection quality or noise.
They work because they each use a single DisplayPort HBR2 x4 connection with DSC.

You can force an LG UltraFine 5K to use a single HBR2 x4 connection but then it would be limited to 5K39 (with a custom timing added to the system).


Minor correction: the displays are dual tile; the connection is dual link SST (not related to dual link DVI). The Apple support documents that mentioned dual link SST can be found on the wayback machine.

For 5K60 dual link SST, the two DisplayPort connections are each sending 2560x2880 60Hz - one for the left half and one for the right half of the display. I think the signals may be synced such that each line from each half are sent nearly at the same time so they can be drawn on the 5120x2880 screen at the same time. I'm not sure how synced they need to be if at all. I suppose one could try sending two unsynced 2560x2880 signals (if you can convince the system that the two connections are not part of a multi-tile display - which would involve modifying the EDIDs of each tile before the system sees them).

Thanks this is effectively what I thought they were doing.

The connect 10G hasn’t been I stock for 2-3 years and also the link not working so i would hope on that. Maybe then a owc or sonette 10GbE

There is a new USB4 10G ethernet adapter that has popped up made by IO Crest. Using the Marvell AQC113 Chipset, which MacOS supports natively. I'm going to pick one up to test.

 

[apple_sheep]

When will Caldigit come out with a Thunderbolt 5 Dock??? Screw the hub.

 

[novagamer]

Any news on the other dock solutions? I haven’t seen much recently. Interested if the new chipset is worth waiting for, who will incorporate it, etc.

 

[Jonas Danielsson]

Thanks this is effectively what I thought they were doing.

There is a new USB4 10G ethernet adapter that has popped up made by IO Crest. Using the Marvell AQC113 Chipset, which MacOS supports natively. I'm going to pick one up to test.

Yes I seen that but I never heard that company and usb on the same side as rj45 is not super. I don’t know about supper , drivers etc how well it will work

but the price is good.

I also seen QNAP has released a similar which is a brand I know at least. But it’s also most twice the price but for me I rather pay once and cry once

 

[facedmurkroots]

Still using my TS3+ dock. Phenomenal investment and nearly a must-buy for any of the 2016-2021 MacBooks. I do wonder if I’ll need to buy a replacement in the future with the now restored port selection on the new MBP family.

Everyday at work though I’m reminded of the PITA that is plugging in and out a bunch of cables across two machines though. Something to be said about the convenience of one single TB cable doing everything.

 

[PaulD-UK]

@facedmurkroots "I do wonder if I’ll need to buy a replacement in the future..."

If your external devices are Thunderbolt, then the TS3+ is showing it's age, and you will have to buy into TB4/5 to get the TB-hub and higher bandwidth advantages.

If you connect USB 3.* devices, then the TS3+ is still the best possible dock, as ALL TB 4/5 docks limit the total bandwidth of all the USB 3 devices to 10Gbps, which all ports share (including ethernet and audio).

But the TS3+ can allocate 10Gbps to more than one USB 3 hub internally, so if you are not using the bandwidth for TB3, then additional USB 3 ports can use it instead. That's why the TS3+ can support so many ports. §

Also, all TB 4/5 hubs still use the Macs host USB 3.* controller, but the Caldigit has it's own USB 3 controllers, so any incompatibilities that attached SSAs/HDs have when directly attached to the Mac are minimised if you attach them to the dock, which is using it's own controller(s).

§ The ability to share additional bandwidth is limited to first generation TB 3 'Alpine Ridge' docks. After about 2018 Intel introduced the 'Titan Ridge' TB 3 chipset, which limits all USB 3.* ports to 10Gbps maximum (with additional bandwidth going towards allowing a second 4K display).

 

[facedmurkroots]

@facedmurkroots "I do wonder if I’ll need to buy a replacement in the future..."

If your external devices are Thunderbolt, then the TS3+ is showing it's age, and you will have to buy into TB4/5 to get the TB-hub and higher bandwidth advantages.

If you connect USB 3.* devices, then the TS3+ is still the best possible dock, as ALL TB 4/5 docks limit the total bandwidth of all the USB 3 devices to 10Gbps, which all ports share (including ethernet and audio).

But the TS3+ can allocate 10Gbps to more than one USB 3 hub internally, so if you are not using the bandwidth for TB3, then additional USB 3 ports can use it instead. That's why the TS3+ can support so many ports. §

Also, all TB 4/5 hubs still use the Macs host USB 3.* controller, but the Caldigit has it's own USB 3 controllers, so any incompatibilities that attached SSAs/HDs have when directly attached to the Mac are minimised if you attach them to the dock, which is using it's own controller(s).

§ The ability to share additional bandwidth is limited to first generation TB 3 'Alpine Ridge' docks. After about 2018 Intel introduced the 'Titan Ridge' TB 3 chipset, which limits all USB 3.* ports to 10Gbps maximum (with additional bandwidth going towards allowing a second 4K display).

That’s interesting to know. I wasn’t aware of how it all was managed internally.

For my use I’m not sure I come close to maxing it out. I use a 27” BenQ 114hz monitor, WD Elements 4TB drive for Time Machine and a couple of USB accessories that don’t draw much power.

 

[joevt]

@facedmurkroots "I do wonder if I’ll need to buy a replacement in the future..."

If your external devices are Thunderbolt, then the TS3+ is showing it's age, and you will have to buy into TB4/5 to get the TB-hub and higher bandwidth advantages.

If you connect USB 3.* devices, then the TS3+ is still the best possible dock, as ALL TB 4/5 docks limit the total bandwidth of all the USB 3 devices to 10Gbps, which all ports share (including ethernet and audio).

But the TS3+ can allocate 10Gbps to more than one USB 3 hub internally, so if you are not using the bandwidth for TB3, then additional USB 3 ports can use it instead. That's why the TS3+ can support so many ports. §

Also, all TB 4/5 hubs still use the Macs host USB 3.* controller, but the Caldigit has it's own USB 3 controllers, so any incompatibilities that attached SSAs/HDs have when directly attached to the Mac are minimised if you attach them to the dock, which is using it's own controller(s).

§ The ability to share additional bandwidth is limited to first generation TB 3 'Alpine Ridge' docks. After about 2018 Intel introduced the 'Titan Ridge' TB 3 chipset, which limits all USB 3.* ports to 10Gbps maximum (with additional bandwidth going towards allowing a second 4K display).

The TS3+ has only one fully capable USB 10 Gbps port - which is the downstream Thunderbolt 3 port. This port is ≈9.7 Gbps.
The USB 10 Gbps port from the ASMedia ASM1142 in the TS3+ is limited to ≈7.877 Gbps.
The rest of the ports of the TS3+ come from two Fresco Logic FL1100 USB 3.0 (USB 5 Gbps) controllers ≈ 4 Gbps.
USB 3.0 from the USB-A port of the ASM1142 is slightly faster than USB 3.0 from the FL1100 ports. I don't know what the USB-A port doesn't have the same max speed as the USB-C port from the ASM1142.

TS3+ can do 9.7 Gbps + 7.877 Gbps + 4 Gbps + 4 Gbps = 25.577 Gbps of USB which is slightly more than Thunderbolt 3 is capable.

A Titan Ridge (newer Thunderbolt 3) or Goshen Ridge (Thunderbolt 4) hub/dock is limited to 9.7 Gbps of USB but at least in that case all the ports are usually capable of near 9.7 Gbps when all the other ports are idle.

Goshen Ridge and Barlow Ridge (Thunderbolt 5) do have their own USB 3.x controllers that will get used if they are connected to a Thunderbolt 3 dock/hub/host.

The USB 3.x controller of Barlow Ridge (e.g. CalDigit Element 5 Hub) can do USB 20 Gbps (≈ 19.39 Gbps). It's an easy way to add 20 Gbps USB to an Intel Mac.

 

[jlforester]

A interesting limitation with this hub is that it will not support 2 x 27” 5K LG Ultrafine displays but will support 2 x Apple Studio displays ( the info is in their notes in very small writing). Both are Thunderbolt 3 interfaces, so what is the problem? This is not indicated for the OWC Thunderbolt 5 Hub, but I am having trouble getting it to support an LG 5K 27” Ultrafine display and an Apple Studio monitor on the same OWC hub.

One thing of note that is never made clear is that all the ports on this hub share the 80 Gb/s interface to the host so you can not have all the ports on the hub using their maximum supported bandwidth. So if you have, for example, 2 5K 60Hz monitors on the hub, they will consume approximately 2 x 28 Gb/s (the data requirements for 5K 60 Hz monitors) leaving 24 Gb/s maximum for all the other ports. I am not sure how the so called 120 Gb/s uni directional support in TB 5 is supported when mixed with bidirectional TB peripherals on a single TB 5 host port but I am researching this now. Something worth bearing in mind.

I'm curious about this limitation as well. I have both a 5K LG and a Studio Display. I'm running both on an M4 Max MBP with the Studio Display connected to an OWC dock and the LG directly to the MBP (since the OWC has only a single outbound TB3 port). This is the only thing that's making me hesitate about getting the TS5 Plus.

 

[jlforester]

you are unfortunately very right about the reliability issues

I would like to see these 10GbE ports implemented with an SFP+ port pre-populated with a RJ45 SFP that I could replace with a 10GBase-SR fiber SFP. Not sure how much that would add to the cost, and is probably a niche use case anyway, but would be really cool.

 

[CalDigitDalton]

I'm curious about this limitation as well. I have both a 5K LG and a Studio Display. I'm running both on an M4 Max MBP with the Studio Display connected to an OWC dock and the LG directly to the MBP (since the OWC has only a single outbound TB3 port). This is the only thing that's making me hesitate about getting the TS5 Plus.

I believe this still wouldn't work through a dock, regardless of Thunderbolt version. The 5k LG is greedy in how it negotiates its monitor connection, so it ends up taking more than half the available video lanes on both TB4 and TB5, which is the root of the issue. The Studio Display uses exactly half, so there's just not enough video lanes available. It doesn't really matter that there's more bandwidth in this situation, because neither monitor can take advantage of it. Only newer DisplayPort 2.1 monitors would be able to leverage the extra bandwidth.

 

[joevt]

I'm curious about this limitation as well. I have both a 5K LG and a Studio Display. I'm running both on an M4 Max MBP with the Studio Display connected to an OWC dock and the LG directly to the MBP (since the OWC has only a single outbound TB3 port). This is the only thing that's making me hesitate about getting the TS5 Plus.

I explained the limitation at https://forums.macrumors.com/thread...-hub-with-thunderbolt-5.2448476/post-33709721

I believe this still wouldn't work through a dock, regardless of Thunderbolt version. The 5k LG is greedy in how it negotiates its monitor connection, so it ends up taking more than half the available video lanes on both TB4 and TB5, which is the root of the issue. The Studio Display uses exactly half, so there's just not enough video lanes available. It doesn't really matter that there's more bandwidth in this situation, because neither monitor can take advantage of it. Only newer DisplayPort 2.1 monitors would be able to leverage the extra bandwidth.

Thunderbolt 4 hubs/docks don't have 3 DisplayPort outputs unless they include a DisplayPort MST hub. macOS doesn't support DisplayPort MST for multiple displays.

Thunderbolt 5 hubs/docks do have 3 DisplayPort outputs but all Macs, including Apple Silicon Macs that support Thunderbolt 5, only have 2 DisplayPort connections per Thunderbolt bus from the GPU. The LG UltraFine 5K requires two connections for 5K60. I suppose if you connect the Apple Studio Display first, and the LG UltaFine 5K display second, then the LG UltraFine 5K might take only one DisplayPort output and then will be limited to 4K60 unless you add a custom timing for 5K39. Alternatively, if you connect the LG UltraFine 5K with a 20 Gbps Thunderbolt cable or with a USB-C cable that doesn't allow Thunderbolt 40 Gbps, then the LG UltraFine 5K can be connected first and will only take one DisplayPort connection (still limited to 4K60 or 5K39). The Apple Studio Display supports DSC so it will get 5K60.

One method to add DisplayPort outputs is to use a DisplayLink adapter but this is not a connection to the GPU - it requires the CPU to compress video data and send it over USB 3.0.

PCs that support Thunderbolt 5 may be able to support 3 DisplayPort outputs from a Thunderbolt 5 dock/hub if they have a Thunderbolt 5 controller with 3 DisplayPort inputs from the GPU.
However, Intel says Thunderbolt 5 only needs to support two displays so a Thunderbolt 5 PC might not have support for 3 displays from a Thunderbolt 5 port. But Windows and Linux support MST, so you could have a Thunderbolt 5 dock with support for like six 4K60 displays (3 per MST hub) depending on the GPU.

 

[whitby]

I'm curious about this limitation as well. I have both a 5K LG and a Studio Display. I'm running both on an M4 Max MBP with the Studio Display connected to an OWC dock and the LG directly to the MBP (since the OWC has only a single outbound TB3 port). This is the only thing that's making me hesitate about getting the TS5 Plus.

It turns out that the issue is a limitation in the Apple implementation of the Thunderbolt 5 interface. It only supports 2 display port channels. The LG 5K display, because it is an older Thunderbolt 3 interface display, uses two display port channels to provide the 5K display, thus using all available display port channels on the Thunderbolt 5 port. Windows machines implement the Intel spec and provide 3 display port channels on their Thunderbolt 5 ports and thus do not have this limitation. Also of note is that the Apple studio monitor not only uses one display port channels for 5 K (since it is based on a Thunderbolt 4 data rates) but also implements display port channel compression reducing the bandwidth requirement to around 9Gb/s I think. Thus you must devote one entire TB 5 port to the LG 5K display and place the Studio on another port, somewhat wasteful of bandwidth and resources.

Thunderbolt interfaces are a minefield of compromises and technical limitations that make the interface much less useful than you might think, especially when manufacturers do not fully implement the interface (as in this case with Apple’s display port channel limitations in their implementation of TB5).