3 ms·
Actual example of this: Back in the Thunderbolt 3 era, it was up to each motherboard manufacturer to decide how many pairs they routed to USB alt-mode, so it's
by altairprime 3y ago
Actual example of this:
Back in the Thunderbolt 3 era, it was up to each motherboard manufacturer to decide how many pairs they routed to USB alt-mode, so it's not necessarily a safe bet to depend on it working.
So, in one specific example, 4k60 over USB alt-mode DisplayPort is not supported on Apple's $4999 iMac Pro, as USB alt-mode is only assigned two pairs; however, 4k60 over Thunderbolt DisplayPort is supported, as Thunderbolt is assigned four pairs. The only way to get 4k60 out of that device is to use a Thunderbolt-only DisplayPort adapter, that has no USB mode at all.
This was resolved by USB 4 and Thunderbolt 4 both incorporating a more modern DSC (display stream compression), among other things as described above, but your mileage will vary much more wildly with USB 3.