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ruslan120

macrumors 65816
Original poster
Jul 12, 2009
1,369
1,067
I've been considering a Pro Display XDR for a while now. Given this video, and its conclusion that the Pro Display XDR is an inadequate solution for creative professionals, it's likely they might go on sale (maybe at a reseller).

So - will a Pro Display XDR work if daisy chained to a Caldigit TS3 Dock? Both of my Thunderbolt 3 ports on a 2019 iMac are populated (1 - Caldigit, 2 - eGPU).

If not, it's not the end of the world. I can plug the eGPU into the Caldigit and free up a port. Hoping to keep the extra 10-15% of performance and not do so.
[automerge]1581699180[/automerge]
To guess, I imagine the answer is no. As is, the 6K resolution saturates most of the connection (afaik) and that might cause issues once I plug in other peripherals into the TS3 (solid state drive over USB C (10 gigabits), another 4K display into the displayport (? gbps)).
 

chrfr

macrumors G4
Jul 11, 2009
10,912
4,500
I've been considering a Pro Display XDR for a while now. Given this video, and its conclusion that the Pro Display XDR is an inadequate solution for creative professionals, it's likely they might go on sale (maybe at a reseller).

So - will a Pro Display XDR work if daisy chained to a Caldigit TS3 Dock? Both of my Thunderbolt 3 ports on a 2019 iMac are populated (1 - Caldigit, 2 - eGPU).

If not, it's not the end of the world. I can plug the eGPU into the Caldigit and free up a port. Hoping to keep the extra 10-15% of performance and not do so.
[automerge]1581699180[/automerge]
To guess, I imagine the answer is no. As is, the 6K resolution saturates most of the connection (afaik) and that might cause issues once I plug in other peripherals into the TS3 (solid state drive over USB C (10 gigabits), another 4K display into the displayport (? gbps)).
There isn't enough bandwidth to run the display at full resolution through a hub.
 
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ruslan120

macrumors 65816
Original poster
Jul 12, 2009
1,369
1,067
Thanks for the response / information.

Would you happen to have any good sources as to why? I'm a bit unfamiliar with how Thunderbolt controllers balance bandwidth. I know there's a maximum of 40 gigabits per second but say you have a dock which uses 15 gbps running a SSD and 4K monitor at full tilt, and daisy chains an eGPU, does the dock just hand the remaining bandwidth to the daisy chain TB3 port?
 
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joevt

macrumors 68030
Jun 21, 2012
2,962
1,330
Would you happen to have any good sources as to why? I'm a bit unfamiliar with how Thunderbolt controllers balance bandwidth. I know there's a maximum of 40 gigabits per second but say you have a dock which uses 15 gbps running a SSD and 4K monitor at full tilt, and daisy chains an eGPU, does the dock just hand the remaining bandwidth to the daisy chain TB3 port?
6016 x 3384 x 30 bbp x 60Hz = 36.6 Gbps. Not enough left for USB 3.0. I believe it should still be possible but other threads have shown that Apple does not allow the XDR to use dual HBR3 connection more than a single hop away from the source Titan Ridge Thunderbolt 3 controller (your iMac). In the case of your iMac, the XDR needs to be connected to one of the Thunderbolt ports, and everything else needs to be connected to the other Thunderbolt port (most eGPUs only have a single Thunderbolt 3 port, so you may have to make a custom eGPU with two Thunderbolt 3 ports using a Thunderbolt PCIe expansion box and external power supply).

 
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