Any good Thunderbolt dock with multiple ports?

[simpn]

Hey!

I'm looking for a decent Thunderbolt dock that will be able to charge my MBP 13" Intel (2021) and supports the following setup:

- 5K@60Hz display (via TB cable)
- 1920x1200@60Hz (via DisplayPort to USB-C cable)
- USB-C NVMe drive
- ~4 USB peripherals like keyboard, mouse, tablet or charging some devices over USB
- Gigabit Ethernet

My main concerns:
- Can I run them all on one Thunderbolt dock/cable without any bandwidth/power issues?
- Does Catalina support such docks? I found information that TB docking stations require BigSur.
- Will the USB-C NVMe drive maintain ~1GB/s data transfer?
- What if I upgraded a USB-C NVMe SSD drive to TB NVMe? Will it run at full speed (~2-3GB/s) or will it be limited due to connected 5K/2K displays?


I found some new docks released this year. CalDigit Thunderbolt 4 Element or OWC Thunderbolt Dock look very suited to my needs. The OWC is even better with LAN/SD/Audio ports which I would also use! So, can all ports be used at the same time in the dock like OWC/CalDigit? Or is it rather a wish for random kernel panics?

CalDigit description mentions a Big Sur requirement. No information about this on the OWC product though. Is this also a requirement for the OWC dock?

Thanks

 

[joevt]

If the 5K display is an LG UltraFine 5K, then you cannot connect another display because the LG UltraFine 5K uses both DisplayPort connections. In that case you would need to connect the other display to some other port of the MBP (or you could try a DisplayLink adapter or a eGPU Breakaway Puck RX 5500 XT/5700).
https://www.sonnettech.com/product/egpu-breakaway-puck/overview.html
https://www.displaylink.com

Thunderbolt is 40 Gbps. 5K is ≈ 29 Gbps. That leaves ≈ 11 Gbps for write speed but you should still get ≈ 22 Gbps for read speed. A USB-C NVMe can't use more than 9.7 Gbps (≈1 GB/s). A Thunderbolt NVMe will have limited write speed (up to 11 Gbps) but there are some NVMe devices that don't get more than 8 Gbps for Thunderbolt write speed.

Thunderbolt has been around since 2011 so Catalina does support Thunderbolt docks.

A Thunderbolt 4 dock requires Big Sur for full functionality, so you'll probably want to stick with Thunderbolt 3 docks. for Catalina, you might be able to connect a Thunderbolt 4 dock before boot but you cannot do hot plug of Thunderbolt devices to that after boot.

You cannot connect a Thunderbolt NVMe and a LG UltraFine 5K Thunderbolt display at the same time with Thunderbolt 3. An LG UltraFine 4K has two Thunderbolt ports but the LG UltraFine 5K only has one.

The LG UltraFine displays have USB 3.0 ports (4 Gbps total ≈ 460 MB/s).

 

[simpn]

Thanks for the very detailed answer!

If the 5K display is an LG UltraFine 5K, then you cannot connect another display because the LG UltraFine 5K uses both DisplayPort connections.

Yes, the 5K display is LG UltraFine 5K. I'm not sure if I understand the limitation, I have no problems connecting both 5K and 2K on the same side of the laptop. It works fine. The only problem is connecting order. First 2K, then 5K.

Thunderbolt is 40 Gbps. 5K is ≈ 29 Gbps. That leaves ≈ 11 Gbps for write speed but you should still get ≈ 22 Gbps for read speed. A USB-C NVMe can't use more than 9.7 Gbps (≈1 GB/s). A Thunderbolt NVMe will have limited write speed (up to 11 Gbps) but there are some NVMe devices that don't get more than 8 Gbps for Thunderbolt write speed.

Hm, just found the new Sonnet Echo 11 Thunderbolt 4 dock. It clearly states that you can connect 2x5K on a single Thunderbolt. Is it really possible? They didn't mention using the NVMe disk at the same time though.

A Thunderbolt 4 dock requires Big Sur for full functionality, so you'll probably want to stick with Thunderbolt 3 docks. for Catalina, you might be able to connect a Thunderbolt 4 dock before boot but you cannot do hot plug of Thunderbolt devices to that after boot.

Could you explain or provide a reference to the missing features in Catalina? I don't understand what is not compatible with the OS. Using more than 1 TB port on the hub/dock?

The LG UltraFine displays have USB 3.0 ports (4 Gbps total ≈ 460 MB/s).

This is a bummer! I just realized that there is no way to achieve what I would like, so I started thinking about plugging a USB-C hub into the LG display. Then the USB-C NVMe, and other peripherals to it. Does it look like there is no real alternative for having a single cable other than upgrading to Big Sur?

 

[joevt]

Yes, the 5K display is LG UltraFine 5K. I'm not sure if I understand the limitation, I have no problems connecting both 5K and 2K on the same side of the laptop. It works fine. The only problem is connecting order. First 2K, then 5K.

You are using the 5K display in 4K mode. Use SwitchResX to see the actual resolution of the display timing that you have chosen.
For 5K mode, the LG UltraFine 5K uses two DisplayPort connections over Thunderbolt - one connection is for the left side of the display. The other connection is for the right side of the display. each connection is doing 2560x2880.
"Looks like 2560x1440" will look much better when the display is receiving 5K instead of 4K. Therefore, the LG UltraFine 5K should be connected to one side of the computer and the other display should be connected to the other side of the computer. Actually, that can't work since the MBP Intel graphics can only support 3 displays, and the internal display counts as one of them, and the 5K display counts as two. Maybe you can remove the internal display by closing the lid? If you could do that, then the Apple tech specs would mention it?

Hm, just found the new Sonnet Echo 11 Thunderbolt 4 dock. It clearly states that you can connect 2x5K on a single Thunderbolt. Is it really possible? They didn't mention using the NVMe disk at the same time though.

At a bare minimum, 5120x2880 requires 21.2 Gbps for 60Hz 8bpc RGB so you can't connect two of those to Thunderbolt unless you lower the refresh rate or the vertical resolution.

If the 5K displays are 5120x2160 or 5120x1440 (ultra wide, not HiDPI) then you could connect two of them.

You could maybe connect two Apple 6K displays because they support Display Stream Compression (DSC). I think the MBP 13 inch supports DSC but only has enough resources to connect one 6K display.

You could maybe connect two LG UltraFine 5K by connecting the 2K display first, then the 5K, then a second 5K. Then you can use SwitchResX to set them to 5120x2880 39Hz. If you don't use a Thunderbolt 4 dock, then one of the displays would need to be connected via DisplayPort instead of Thunderbolt (use a cable like the Belkin Charge and Sync cable to include USB 2.0). In that case, you could connect the DisplayPort connected LG UltraFine 5K first and skip the 2K display connection.

Could you explain or provide a reference to the missing features in Catalina? I don't understand what is not compatible with the OS. Using more than 1 TB port on the hub/dock?

Catalina doesn't understand that a Thunderbolt 4 dock/hub has 3 downstream Thunderbolt ports and won't enable them properly for hot plug.
Before Catalina boots, the EFI boot environment might be able to initialize the Thunderbolt 4 dock to make the connected devices work, and Catalina will be able to use those devices, but you can't disconnect and reconnect them.

This is a bummer! I just realized that there is no way to achieve what I would like, so I started thinking about plugging a USB-C hub into the LG display. Then the USB-C NVMe, and other peripherals to it. Does it look like there is no real alternative for having a single cable other than upgrading to Big Sur?

A single cable can work for two 4K displays and a Thunderbolt or USB-C NVMe.
5K requires some compromises.

 

[simpn]

You are using the 5K display in 4K mode. Use SwitchResX to see the actual resolution of the display timing that you have chosen.
For 5K mode, the LG UltraFine 5K uses two DisplayPort connections over Thunderbolt - one connection is for the left side of the display. The other connection is for the right side of the display. each connection is doing 2560x2880.
"Looks like 2560x1440" will look much better when the display is receiving 5K instead of 4K. Therefore, the LG UltraFine 5K should be connected to one side of the computer and the other display should be connected to the other side of the computer. Actually, that can't work since the MBP Intel graphics can only support 3 displays, and the internal display counts as one of them, and the 5K display counts as two. Maybe you can remove the internal display by closing the lid? If you could do that, then the Apple tech specs would mention it?

I don't think so. I can choose the native 5120x2880. No problem. Also, the working area is the same when I only connect the 5K or paired with the 2K.

You could maybe connect two LG UltraFine 5K by connecting the 2K display first, then the 5K, then a second 5K. Then you can use SwitchResX to set them to 5120x2880 39Hz. If you don't use a Thunderbolt 4 dock, then one of the displays would need to be connected via DisplayPort instead of Thunderbolt (use a cable like the Belkin Charge and Sync cable to include USB 2.0). In that case, you could connect the DisplayPort connected LG UltraFine 5K first and skip the 2K display connection.

Personally, I don't plan to connect 2x5K + 2K. I only mentioned Sonnet Echo as it clearly says 2x5K can be connected using BigSur. Here is a detailed compatibility spec: https://www.sonnettech.com/support/downloads/manuals/Thunderbolt_4_Dock_Compatiblity.pdf

They didn't mention the refresh rate so maybe that's the point. If so, and they run at 30Hz, there is not much difference to OWC/CalDigit/etc products.

Catalina doesn't understand that a Thunderbolt 4 dock/hub has 3 downstream Thunderbolt ports and won't enable them properly for hot plug.
Before Catalina boots, the EFI boot environment might be able to initialize the Thunderbolt 4 dock to make the connected devices work, and Catalina will be able to use those devices, but you can't disconnect and reconnect them.

Interesting. Sonnet mentioned it doesn't support hot plug when using 2x5K. Then, why wouldn't it work on Catalina?

A single cable can work for two 4K displays and a Thunderbolt or USB-C NVMe.
5K requires some compromises.

Yeah, but I'm disappointed with the "USB-C" downstream ports on the LG back. You can't even use it for an external drive

 

[joevt]

I don't think so. I can choose the native 5120x2880. No problem. Also, the working area is the same when I only connect the 5K or paired with the 2K.

You cannot connect the 5K and the 2K and get 5K60. Use SwitchResX to show the actual output resolution. It will say you are getting only 4K.
macOS only tells you the framebuffer size and framebuffer pixel depth/format. It does not tell you the output resolution and output pixel depth/format. The GPU can scale up or scale down the framebuffer to produce an output signal. The display can scale up or scale down the input signal to match its native resolution.

I only mentioned Sonnet Echo as it clearly says 2x5K can be connected using BigSur. Here is a detailed compatibility spec: https://www.sonnettech.com/support/downloads/manuals/Thunderbolt_4_Dock_Compatiblity.pdf

They didn't mention the refresh rate so maybe that's the point. If so, and they run at 30Hz, there is not much difference to OWC/CalDigit/etc products.

All the Thunderbolt 4 docks have the same capabilities - they all use the same Goshen Ridge Thunderbolt controller chip.

Interesting. Sonnet mentioned it doesn't support hot plug when using 2x5K. Then, why wouldn't it work on Catalina?

That Sonnet Thunderbolt 4 compatibility spec is kind of useless because they don't mention refresh rate, color depth (8bpc or 10bpc), pixel format (RGB/4:4:4, 4:2:2, 4:2:0), single tile or dual tile.
The LG UltraFine 5K is a dual tile display (the tiles are 2560x2880x2=5K60) which can accept a single tile signal (4K60, or 5K39).
That note about the 2x5K probably means they are talking about dual tile 5K displays that are running in single tile mode.

I said a Thunderbolt 4 dock can work in Catalina, but you can't disconnect/reconnect (hot plug) devices after boot. A Thunderbolt 4 dock/hub won't appear properly in the Thunderbolt tab of System Information.app in Catalina.

Yeah, but I'm disappointed with the "USB-C" downstream ports on the LG back. You can't even use it for an external drive

Yeah, they cheeped out on a USB 3.0 hub when they could have used a USB 3.1 gen 2 hub. Well, you can connect a USB 3.1 gen 2 hub to the downstream Thunderbolt port of an LG UltraFine 4K but the 5K doesn't have a second Thunderbolt port. In that case, a Thunderbolt 4 dock/hub and Big Sur will do the job.

 

[Yohent]

Yeah, they cheeped out on a USB 3.0 hub when they could have used a USB 3.1 gen 2 hub. Well, you can connect a USB 3.1 gen 2 hub to the downstream Thunderbolt port of an LG UltraFine 4K but the 5K doesn't have a second Thunderbolt port. In that case, a Thunderbolt 4 dock/hub and Big Sur will do the job.

Oh my god, that's how it is.

 

[joevt]

Oh my god, that's how it is.

Well, maybe there weren't any good USB 3.1 gen 2 hubs when they designed the LG UltraFine displays?
Or they didn't want people to notice that a couple 4K displays would reduce the USB 3.1 gen 2 write speed slightly.