XPS 15 7590 Docking Station

@margokw15  never mind, it looks like I already answered this when you created a separate thread to ask the same question here.  I didn't notice the date and that @AndiRock had bumped an old thread.

But @AndiRock hopefully the answers above help if you have the same questions (and also help @chellekell  even if they're a few months late relative to the original post.)  I also went into a pretty detailed dock discussion in this thread -- Page 2 is probably more worthwhile for anyone who finds this thread wondering about these docks.  One post I wrote on Page 2 addresses all of these docks and a few other models and exactly how they work, particularly relative to each other.

Ok, one last post.  For anyone else who finds this thread just hoping for info about docking station options for the XPS 15 models, you might find this thread more useful, since the current thread began by someone asking about a dock model that was never really meant to be an ideal pairing with an XPS 15.

@chellekell, @AndiRock , and @margokw15 , I'll answer these questions.  The short version is that if you only need to worry about an XPS 15 rather than needing a single dock that will support that system and something like a Precision 7000 Series model, you really don't want to use a WD19DC.  When you only connect one of the WD19DC's ports to the system, it operates as a regular WD19 180W.  That means two things.  First, you're wasting your money on a WD19DC since a WD19 180W is cheaper, and second, a WD19DC paired with an XPS 15 will have significantly reduced display support capabilities.  The WD19DC is a "dual USB-C dock" -- NOT a Thunderbolt dock! -- which means its advertised display support capabilities require that both connections are active and providing video data.  When only one connection is active, it's just a regular WD19 USB-C dock.  By comparison, the WD19TB is an actual Thunderbolt dock, which means it can do much more in terms of display setups with a single connection than a regular USB-C dock, because a Thunderbolt dock gets access to 4x more video bandwidth than a regular USB-C dock when used with a system like the XPS 15.  (The video bandwidth available to the WD19DC when both connections are active relative to the WD19TB depends on the version of DisplayPort over USB-C that the system you're using supports, but that's a whole other discussion.)  More info below:

1. The WD19DC will only deliver 210W when both ports are plugged in, but it will also only do that for systems that will actually draw it.  The XPS 15 will only ever draw 130W, so even if the WD19DC could deliver more than 130W over a single connection, the XPS 15 would never benefit from that capability being available.  And fyi even then 130W that the WD19TB can provide is already above the 100W max of the official USB Power Delivery spec.  Dell did something proprietary to stretch the spec to carry 130W over a single cable, but 210W would be way more than that.

2. The TB16 might work with the newest XPS 15.  It's not uncommon for the system compatibility list of an accessory not to include models older than a certain age or newer than a certain age, because Dell doesn't go back and test that accessory on very old models nor will they always test the accessory with systems models that are introduced after the accessory, especially if there's a newer generation of that accessory itself, as is the case with the TB16 having been replaced by the WD19TB.  But even though the TB16 includes a higher wattage adapter, it doesn't actually provide any more power.  It's still 130W max.  It's just that the TB16 needs a higher wattage input to achieve that because the "upstream" Thunderbolt port on that dock meant to allow you to connect Thunderbolt peripherals is rated to carry more power than on the WD19TB, so the TB16 has to budget for that.  Also note that the TB16 has been a mixed bag at best in terms of customer impressions, while the WD19TB seems to be working much more reliably.  I wouldn't recommend the TB16 at this stage, even if it WERE offiicially confirmed to work with the XPS 15 9570, which it isn't.

3. When used with the XPS 15 7590, the WD19TB doesn't have any major advantages over the TB16 except for apparently having fewer problems -- which admittedly is a significant advantage, albeit not one that shows up in the specs.  But apart from that, the WD19TB has a different port layout, a modular design (more interesting to business customers ordering these in large quantities), and support for DisplayPort 1.4 signals from the attached system and to attached displays -- although the XPS 15 7590 only supports DisplayPort 1.2, so that's moot when used with that system.  Might be worthwhile for futureproofing though.  Lastly, the WD19TB is backward compatible with non-Thunderbolt systems at a functional level equivalent to the WD19, while the TB16 doesn't work at all with non-Thunderbolt systems -- so that might be useful if you might use other systems with this dock.  That's a quick rundown.