You said the dock was required in #751 but now you say it's unnecessary.
The dock is required to get the Pro XDR Display
running over Thunderbolt and functioning (i.e. not a black screen). If you don't care about Thunderbolt, the dock is not required and the Belkin cable works fine. I've said this very explicitly a few times now, so I'd suggest you re-read my previous comments carefully if you're still confused.
The TS4 is just for providing more ports (10 Gbps USB ports or 40 Gbps TB4, etc.). It is not required for 6K60 10bpc.
That's not quite right. The TS4 doesn't just provide more ports, it provides high speed ports with 1 cable connected to my PC since it's working over TB4 instead of USB2. I also never said it's required for 6k60 10bpc. It's
well known that can plug in the Belkin cable from the Pro XDR into most modern GPUs to achieve 6k60 10bpc, which is how I've previously used the Pro XDR on Windows for the last 3 years (albeit with slow peripherals).
If you're using Windows or a Belkin cable, then the XDR only uses HBR2 link rate for 6K. That mode requires less bandwidth than 4K because it uses DSC, so the dock still has over 24 Gbps of bandwidth for data devices.
Good to know the TS4 dock has up to 24GB/s of bandwidth for my peripherals, that's awesome. Is there a way I can check what protocol is used for the display to validate that, or a synthetic benchmark I could use to try and saturate the data?
I'm not sure what constraint you need to get around.
There's one JHL8540 controller. It has PCIe 3.0 x4 (≈3500 MB/s) to the CPU but the limit is probably around 24 Gbps (3000 MB/s) to both Thunderbolt ports. It also has dual HBR3 inputs (up to 25.92 Gbps each).
Motherboards with integrated Thunderbolt controller may have higher dual Thunderbolt port bandwidth (such as Ice Lake or Tiger Lake used in laptops - Ice Lake was measured up to 4600 MB/s for two ports of a Thunderbolt controller).
I'm not trying to get around any constraint. I'm making it clear to future readers that despite two USB4/TB4 ports on the Motherboard, there's in fact only one controller whose 40GB/s is shared between both. You'd need a Thunderbolt expansion card to do more if that's important for your use case (it's not for mine). Despite not having a TB4 header on this motherboard, it'll probably work with enough effort with just PCI-E.
Back to the first question, is the Belkin cable sufficient or is the dock required? I suppose just the cable is expensive enough but having to use a Thunderbolt dock is on another level. Really, the XDR should be able to just connect with a Thunderbolt cable to your motherboard's Thunderbolt port. Did you try a normal USB-C (non-Thunderbolt) cable? It would allow Thunderbolt 2 speed of 20 Gbps which is still enough for 6K60 10bpc with DSC. If Thunderbolt 3 is a problem, then maybe so would Thunderbolt 2, except with Thunderbolt 2 there is no possibility of a dual HBR3 connection. Or it may connect as DisplayPort Alt Mode with USB 2.0 like the Belkin cable.
I'm confused about what's not been clear. I'd suggest re-reading my posts a few times and/or asking very pointed questions. Happy to help if I better understand the question.
My best guess of what you're asking is "Do you need the Belkin Cable connected to the TS4 Dock for the dGPU on the Pro Art X670E to work over TB4 if the dGPU is connected to the Pro Art X670E via DisplayPort?" The answer to that question is "Unfortunately, yes" if you want to use the USB-powered controls on the display. If you don't care about the USB controls on the display (or BootCamp Manager), then I'd imagine a high quality USB-C (Pro XDR) to DisplayPort (TS4) cable would suffice. That being said, if you substitute the Belkin Cable for an Intel-certified TB4 cable or Apple's included TB3 cable, then the Pro XDR won't turn on -- regardless if the Motherboard is connected directly to the TS4 Hub or the Pro XDR. As I've mentioned earlier, you can get around this by disconnecting the DisplayPort pass through between the dGPU and Motherboard, which forces the 7950x's iGPU to power the Pro XDR at 6k60 10bpc, which it happily does. But the 7950x has a terrible iGPU, so even scrolling through Chrome at 6k60 is laggy. And then there's non trivial framebuffer copies between the dGPU and iGPU required to use the dGPU on a per-app basis, which is tedious to set in Windows. So that's not a solution I'm willing to settle for, though may be fine for some people.
If your question is "Do you need the TS4 Dock to achieve 6k60 10bpc using the dGPU?" Then answer to that is obviously "no", but you'll need to connect your high speed peripherals another way. And if you happen to be using multiple computers like I am, you'll need to be OK with constantly connecting those cables to other computers as you work throughout the day.
