I’ve noticed a couple Thunderbolt 3 docks (such as the HP Thunderbolt Dock G2) containing DisplayPort 1.4 MST Hubs. I am wondering why there aren’t any standalone DisplayPort 1.4 MST Hubs yet and will there be any soon?
Currently, for four lane DisplayPort 1.4 support, the HP dock requires a Thunderbolt 3 connection to a computer with a Titan Ridge Thunderbolt 3 controller having Nvidia or AMD graphics supporting DisplayPort 1.4.
The HP dock can instead take input from a USB-C with DisplayPort alt mode port (because the HP dock uses a Titan Ridge Thunderbolt 3 controller), but that only allows two lanes of DisplayPort.
A DisplayPort to USB-C cable does not work with the HP dock. I guess a USB signal is required so four lanes isn’t possible this way.
The only way to get a four lane DisplayPort 1.4 output from a graphics card to the HP dock is to use a GC-TITAN RIDGE. A standalone MST hub would remove this requirement.
One interesting thing a DisplayPort 1.4 MST Hub can do is drive a 5K dual cable DisplayPort 1.2 display (such as the Dell UP2715K) from a single DisplayPort 1.4 signal. The max color depth is reduced from 10 bpc to 8 bpc because DisplayPort 1.4 has only 75% the bandwidth of dual cable DisplayPort 1.2. I have only one such 5K display, so I don’t know if this connection counts as one display or two displays. I do know that an Nvidia graphics card which supports only 4 displays will allow one of the 4 displays to be a 5K dual cable display but I don’t know if two or more of the 4 displays can be 5K dual cable displays.