  The external XPS 8930 Setup and Specifications PDF states =Front USB 3.1 Gen 2 Type-C port provides data transfer speeds up to 5 GbpsRear USB 3.1 Gen 2 Type-C port provides data transfer speeds up to 10 Gbps The internal XPS 8930 training page also states =Front USB 3.1 Gen 2 Type-C port provides data transfer speeds up to 5 GbpsRear USB 3.1 Gen 2 Type-C port provides data transfer speeds up to 10 Gbps If we go by the generic online speed specification of Thunderbolt 3 as 40 Gbps, then I would say it is not true Thunderbolt 3. But you would have to test the transfer speeds and post the results. Before installing the K7JJJ driver;Front USB 3.1 Gen 2 Type-C port transfer speed = ?Back USB 3.1 Gen 2 Type-C port transfer speed = ? After installing the K7JJJ driver;Front USB 3.1 Gen 2 Type-C port transfer speed = ?Back USB 3.1 Gen 2 Type-C port transfer speed = ?
I didn't think the XPS 8930 USB-C ports supported Thunderbolt 3 but then I found under the Chipset category, "Intel Thunderbolt Controller Driver", K7JJJ 17.2.71.250 A05.  which implies it does. Anyone know which one it is for sure? 
XPS 8930, Thunderbolt 3 USB-C?