Studio Display / XDR Owners - anyone getting "Thunderbolt 5" as the "Mode"?

[Vladie]

In "System Information", under "Hardware > Thunderbolt/USB4", is anyone with the new Studio Display (or Studio Display XDR) seeing "Thunderbolt 5" as the "Mode" when selecting the Studio Display? All I get is "USB4 v2". Mac Mini M4 Pro, so, yes, it has Thunderbolt 5 ports. The original cable is too short, so I purchased the Cable Matters Active Thunderbolt 5 Cable 2m, but still just seeing "USB4 v2". I played around with the new Studio Displays at the local Apple Store, but, again, only saw "USB4 v2".

I've read the threads with people having issues daisy chaining and/or with 120Hz (on the XDR obv) but I didn't see anyone discussing this specific issue, so I don't know if it has any bearing on any issue anyone is actively struggling with.

If anyone does actually see "Thunderbolt 5", which cable are you using? Is anyone seeing it with a 2m cable (e.g. Cable Matters, OWC or CalDigit)?

I did note this Reddit post detailing an apparent bug (from the comments appears still present in 26.4) where NON-Max processors (e.g. my M4 Pro) fail some firmware check from the Thunderbolt 5 switch controller inside the Studio Display:

https://www.reddit.com/r/mac/comments/1rzafpz/troubleshooting_the_studio_xdr_with_claude_code

I don't know if getting the "Mode" to show "Thunderbolt 5" means anything, but I appreciate anyone taking the time to look into it and replying.

 

[thenewepic]

All I get is "USB4 v2"

"Thunderbolt 5" is the same as "USB4 v2".
Also "Thunderbolt 4" is "USB4".

 

[Vladie]

"Thunderbolt 5" is the same as "USB4 v2".
Also "Thunderbolt 4" is "USB4".

I appreciate the response, but I don't think that's correct. Thunderbolt 5 - at least AFAIK - allows for up to 120 Gbps transmit and 40 Gbps receive (e.g. bidirectional communication) for displays, while USB4 v2 caps bidirectional communications at 80 Gbps each way, with 120 Gbps being only unidirectional.

I also note that the speed for USB4 v2 is listed as "80 Gb/s" in the System Information, while the downstream Thunderbolt 5 port is showing "Up to 120 Gb/s". I was expecting the same "Up to 120 Gb/s" language for the upstream connection if it really was negotiated as Thunderbolt 5.

I know that the display itself (especially the non-XDR version that is limited to 60Hz) doesn't need that speed, but I assumed that if both the computer and the display had Thunderbolt 5, and the cable was Thunderbolt 5 certified, that they'd negotiate Thunderbolt 5 ("Up to 120 Gb/s") because that was the max capability.

I guess until someone replies that they have something other than "USB4 v2", I'll just assume I'm wrong.

 

[thenewepic]

Thunderbolt 5 - at least AFAIK - allows for up to 120 Gbps transmit and 40 Gbps receive (e.g. bidirectional communication) for displays, while USB4 v2 caps bidirectional communications at 80 Gbps each way, with 120 Gbps being only unidirectional

where did you get this information from? It's wrong. Please, read this.
I will even quote important part:

Optionally for certain applications, such as driving very-high performance USB4-based displays, the USB Type-C signal interface can be configured asymmetrically to deliver up to 120Gbps in one direction while retaining 40Gbps in the other direction.

Basically Thunderbolt 5 is a full implementation of USB4v2 specification.

I guess until someone replies that they have something other than "USB4 v2", I'll just assume I'm wrong

macOS doesn't show "Thunderbolt 5". It doesn't show "Thunderbolt 4" either. I have a Mac with TB4 support and a TB4 device and there is no "Thunderbolt 4" in the system report, just "USB4".
Because in reality Thunderbolt 4 is not a distinct standard - it's just a complete implementation of USB4, certified by Intel. The same can be said about Thunderbolt 5.

 

[Vladie]

where did you get this information from? It's wrong. Please, read this.
I will even quote important part:

Basically Thunderbolt 5 is a full implementation of USB4v2 specification.

macOS doesn't show "Thunderbolt 5". It doesn't show "Thunderbolt 4" either. I have a Mac with TB4 support and a TB4 device and there is no "Thunderbolt 4" in the system report, just "USB4".
Because in reality Thunderbolt 4 is not a distinct standard - it's just a complete implementation of USB4, certified by Intel. The same can be said about Thunderbolt 5.

Thank you for the correction. My information came from a Gemini summary, and, given that it dovetailed with the screenshot I posted, I did not double-check further. Mea culpa.

But my confusion remains. As you've proven, USB4 v2 is capable of the same "Up to 120 Gb/s" that Thunderbolt 5 is. So why is the "Speed" not showing that? It's almost like some hardware failed some handshake somewhere.

Does anyone with a TB5 mac (and a Studio Display / XDR) see "Up to 120 Gb/s" in the upstream speed?

I have not tried it with the 1m cable that came with the display (it's too short for my setup), but I did purchase the new "Active" "Intel-Certified" "Thunderbolt™ 5" 2m cable from Cable Matters and the speed shown is no different ("80 Gb/s") than my old, generic USB4 cable (at less than half the price). FWIW.

 

[thenewepic]

Does anyone with a TB5 mac (and a Studio Display / XDR) see "Up to 120 Gb/s" in the upstream speed?

as I understood, when there is no device connected the system report says "Up to 120 Gb/s". Which means the port is capable of handling 120 Gbit. But by default devices rather negotiate symmetrical 80 Gbit.
This seems logical because it's more typical use case.
I think that to be connected by asymmetrical connection a user should use a really demanding display. Studio Display XDR is not that demanding. 80 Gbit is more than enough to drive 5K@120 even without DSC and you still have more than 20 Gbit to spare.
Maybe if you daisy-chain two Studio XDRs you will get asymmetrical mode on the TB port of your Mac. But I'm not sure because I didn't see real-world application of the asymmetrical mode anywhere.
As for your original post:

I did note this Reddit post detailing an apparent bug (from the comments appears still present in 26.4) where NON-Max processors (e.g. my M4 Pro) fail some firmware check from the Thunderbolt 5 switch controller inside the Studio Display

I have to say that "some firmware check failing" is just an AI hallucination. MBP M4Pro doesn't support more than one Studio Display XDR: https://support.apple.com/en-us/101571
Yes, the answer is indeed very simple.

 

[Vladie]

as I understood, when there is no device connected the system report says "Up to 120 Gb/s". Which means the port is capable of handling 120 Gbit. But by default devices rather negotiate symmetrical 80 Gbit.
This seems logical because it's more typical use case.
I think that to be connected by asymmetrical connection a user should use a really demanding display. Studio Display XDR is not that demanding. 80 Gbit is more than enough to drive 5K@120 even without DSC and you still have more than 20 Gbit to spare.
Maybe if you daisy-chain two Studio XDRs you will get asymmetrical mode on the TB port of your Mac. But I'm not sure because I didn't see real-world application of the asymmetrical mode anywhere.
As for your original post:

I have to say that "some firmware check failing" is just an AI hallucination. MBP M4Pro doesn't support more than one Studio Display XDR: https://support.apple.com/en-us/101571
Yes, the answer is indeed very simple.

Your follow-up explanation makes a lot of sense. The 80 Gbit bi-directional link is probably just the default negotiated unless one device specifically asks for 120 Gbit asymmetrical, which, in my very tame use case of a single, 60Hz 5k display, is certainly not needed. Thank you for taking the time to ruminate further on this with me!

I don't mean to get sidetracked, but I think what you meant to say in regards to the Reddit thread I linked was that the MBP M4Pro doesn't support more than one XDR at 120Hz. In fairness to the poster, they did say they were trying to get 2 XDRs to work at 60Hz, which should be possible.

Nevertheless, I believe my particular question regarding what is shown in the System Information (to which the Reddit thread was only tangentially relevant) has been answered. Once again, thank you for your time and effort!

 

[thenewepic]

In fairness to the poster, they did say they were trying to get 2 XDRs to work at 60Hz, which should be possible

yep, it's a known bug where if a user manually switches the Studio XDR to 60Hz macOS doesn't renegotiate the connection parameters thus cannot use another connected display.
I hope this annoying bug will be fixed soon because this is one of most discussed issues regarding the new monitor.