XPS-17 9700 1080p Best Dock?

@recDNA  Assuming you want your dock to power your system adequately so that you don't have to choose between your system throttling performance due to an undersized dock power source or keeping your XPS 17's own power adapter attached as well, you have two options:

• The Dell WD19 180W w/ 130W passthrough (not the WD19 130W w/ 90W passthrough)
• The Dell WD19TB

The difference is that the former uses regular USB-C, whereas the latter uses Thunderbolt 3.  This creates two practical differences:

• The WD19TB includes a "downstream TB3" port to allow you to attach a Thunderbolt peripheral to the dock itself, such as a fast SSD/storage array or an eGPU.  The WD19 doesn't have this port, so you'd have to connect any other Thunderbolt peripherals directly to the system.
• The WD19TB's use of Thunderbolt 3 means it can access more video bandwidth from the system and therefore can run higher-end display setups compared to the WD19.

You won't have to change any BIOS settings just to use a dock.  What you might have read about is a BIOS option available on XPS 17 builds that include an NVIDIA RTX GPU (not a GTX GPU), which allows the NVIDIA GPU to take direct control of the display outputs.  This can provide some additional capabilities over the default mode of having the Intel GPU directly controlling the outputs with the NVIDIA GPU only operating as a render-only device via NVIDIA Optimus.  This option can be helpful if you need those additional capabilities, such as G-Sync, VR, and additional display bandwidth, but you don't have to enable that option if you don't need those capabilities.  And if you don't have an RTX GPU, then you don't have this option anyway.  But even if you do have this option and you choose to enable it, technically you don't HAVE to switch that BIOS option back when you undock.  You can keep the NVIDIA GPU controlling the display outputs even while undocked, although the fact that this option means that even the built-in display will be directly controlled by the NVIDIA GPU, that setup will impose a battery life penalty because it will mean the NVIDIA GPU can't ever be shut down, even if nothing graphics-intensive is going on.

I mentioned above that one impact of that BIOS option was additional video bandwidth. More specifically, when the system is in the default mode of the Intel GPU controlling the outputs, the system supports DisplayPort 1.2/HBR2 over USB-C/TB3.  If you have an RTX-equipped system and enable that BIOS option, it supports DisplayPort 1.4/HBR3.  The User Guides of the WD19 and WD19TB, both available on support.dell.com, have tables that spell out what display setups are possible with each type of source system, but basically:

• With a system in the default mode of the Intel GPU controlling the outputs:
  • With a WD19, you'd be limited to dual displays up to 1920x1200 60 Hz each, or a single display at 2560x1600 60 Hz (or 4K 30 Hz).
  • With a WD19TB, you can run dual displays up to 4K 60 Hz or triple displays up to 2560x1440 60 Hz each, although you might have to cable the displays to specific combinations of outputs to run high-end display setups like that.  Details in the WD19TB User Guide
• With an RTX-equipped system that has that BIOS option enabled:
  • The WD19 can run dual displays up to 2560x1440 60 Hz each or a single 4K 60 Hz display.
  • The WD19TB can run dual 4K 60 Hz + a single 2560x1440 display.  And here again, there are some restrictions around combinations of outputs you can use if you reach toward this higher end.

If you have more questions, it might help to go into a bit more detail about the display setup you plan to run.

Mine is the XPS17 9700 with 1080p not 4K.  Can a WD19TB somehow allow my 1080p system to output 4K to the monitors?

@recDNA  If you use the external displays in Extend mode rather than Duplicate, then yes.  In Extend mode, each display is treated independently, so the resolution of one display has no effect on the others.

@RACONN  Yes, that's the only difference.  Somehow the global semiconductor shortage affected Dell's ability to incorporate that audio jack or the chipset that runs it, which was preventing them from creating docks.  So they introduced the S variants of their WD19 dock family models that dropped them in order to avoid a huge order backlog.  If you need an audio jack, there are USB audio adapters like this one.  There might be equivalents that use a 3.5 mm headset jack where you can have line-out and mic on the same jack, as is the case with the non-S versions of the docks, but I haven't looked.

Any thoughts on the WD19TBS in comparison to the WD19TB.  I know that the TBS doc does not have the audio pin jack, but is that the only difference?

I have the XPS 17 (9700) with the NVIDIA(R) GeForce RTX(TM) 2060 6GB GDDR6 +Max-Q.  

I want to use (2) 1080x1920 144Hz and (1) 3840x2160 60Hz monitors from this laptop.  Can I do this using the WD19 docking station?

@cparker5 Not with the regular WD19. The XPS 17 9700 with an RTX GPU can be either a DisplayPort HBR2 system (in its default mode) or an HBR3 system (if you enable the BIOS option to have the NVIDIA GPU take direct control of the display outputs), but either way you won’t have enough bandwidth for all of those displays. In HBR2 mode you’d be limited to either single 4K 30 Hz (not 60) or dual 1080p 60 Hz.

But the WD19TB or WD19TBS would be another story. They can run dual 4K 60 Hz with that system regardless of whether it’s running HBR2 or HBR3. So single 4K 60 Hz + dual 1080p at least 120 Hz should also be possible. I’m not sure about 144 Hz specifically since I haven’t done the math on the exact bandwidth requirements of that setup. Note however that the WD19TB has some restrictions on which ports can be used to achieve certain high bandwidth display setups like this, and they vary based on the DisplayPort HBR2 mode of the source system because the WD19TB(S) allocates that bandwidth differently in those cases:

• In HBR2 mode, you’d want to put the 4K 60 Hz display on the downstream TB3 port at the edge of the dock, using a USB-C to DP cable or USB-C to HDMI 2.0 cable if the display doesn’t have a USB-C input. (If it has both DP and HDMI, I’d use DP.). The other two displays can be on any combination of the other outputs except HDMI + the USB-C port right next to it, which can’t be used simultaneously for video output.
• In HBR3 mode, the downstream TB3 port gets LESS dedicated bandwidth than the shared ports, so you can try connecting all displays to ports EXCEPT that one. Otherwise, that downstream TB3 port might be enough to run 1080p 120 Hz, or maybe even 144 Hz. But it definitely won’t be enough for the 4K 60 Hz display.

Thank you very much.  By my calculations, 1920x1080 at 144Hz is just shy of 9Gbs (total).  So If I am looking at the available video bandwidth for HB3 (nearly 26Gbps) it would seem, as you mentioned above that 3840x2160@60Hz (15GBps) and (2)1920x1080@144Hz (9Gbps) would be too much (33Gbps) for HB3.  However, again with your recommended 3840x2160@30Hz (7.5Gbps) and the (2)1080p@144Hz (9Gbps) it would seem I might have better success with that setup (25Gbps). 

I will go with one of the versions of the WD19TB to try and get 3 external monitors going.

I hope I am thinking about the correctly, thank you so much for your help!

Thank you for the clarification and the lesson, very much appreciated!

@cparker5 Happy to help, but there are some misunderstandings here.

First, I wasn’t suggesting that you use 4K 30 Hz. I was just saying that if you used the regular WD19 with the default HBR2 mode of the XPS 17 9700, then 4K 30 Hz would be the most you could achieve. Regular USB-C docks (meaning non-Thunderbolt) that configure the USB-C link to run both video and USB 3.x only get access to two lanes of whatever HBR rate is supported, not a full interface that is defined as four lanes. A Thunderbolt dock can run either 8 lanes of HBR2 (two full interfaces) or 5 lanes of HBR3. It’s also important to make sure you’re being consistent about looking at bandwidth figures that either do or do not incorporate encoding overhead.

Putting those concepts together, a WD19 would have 8.6 Gbps of usable video bandwidth with an HBR2 system or 12.9 Gbps with an HBR3 system. A WD19TB would have 34.5 Gbps with an HBR2 system or 32.4 Gbps with an HBR3 system — again that’s usable bandwidth, not raw bandwidth.

And while I’m at it, I did the math on the displays. A 1080p 144 Hz display should consume about 7.68 Gbps of usable bandwidth, or 15.36 Gbps for two of them. A 4K 60 Hz display requires 12.5 Gbps.

So it looks like you’d be ok for 4K 60 Hz + dual 1080p 144 Hz with the WD19TB or TBS, even after taking into account that the WD19TB and TBS are not infinitely flexible in how they allocate video bandwidth across their ports, which means that it isn’t always enough to have enough bandwidth, but also to have enough bandwidth where you need it. But you should be fine.