Without DSC, the XDR requires dual HBR3 x4 over Thunderbolt using 39 Gb/s of bandwidth. That means the USB ports would be limited to 1 Gbps for writes. Read speed should still allow 4 Gbps.Anyways, what I meant was that, based on what you showed, DSC is not necessary when driving a single XDR. Hence I assumed that, even if a Mac is DSC-capable, it's only going to be using DSC with the XDR when you are driving more than one XDR on a single port (or, more generally, if you are driving an XDR plus any other monitor on that port).
Or is that not correct? Do DSC-capable Macs use DSC when driving only a single XDR on a TB port, even if that's not necessary? And if so, why?
The Dell 6K probably doesn't have a dual HBR3 mode since it has two Thunderbolt ports. Only macOS has the ability to enable dual HBR3 mode as far as I know. The mode is not enabled if there's a Thunderbolt device between the XDR and the host.OTOH, if a single XDR doesn't use DSC even on DSC-capable Macs, what about the 6k Dell?