[NAME]  and anyone else who might be interested, I reached out to [NAME] who was kind enough to run this test on his XPS 15 9500 that had an NVIDIA GPU installed.  When a display was connected through the non-Thunderbolt port on the right, NVIDIA Control Panel showed it as controlled by the Intel GPU.  Same for the TB3 ports on the left.  So Dell doesn't appear to have changed from their standard practice of wiring USB-C/TB3 ports to the Intel GPU (with the semi-exception of the Precision 7000 Series models that allow this to be customized.)Therefore I suspect that the claim in the XPS 15 9500 specs (as of this writing) about the non-Thunderbolt port supporting DisplayPort 1.4 is an error.  The 10th Gen H Series CPU models used in the XPS 15 9500 do not include Intel's new Gen 11 GPU that supports DP 1.4.  They instead still use an older GPU that only supports DP 1.2, so if the Intel GPU controls all outputs, I don't see how the DP 1.4 support claim could be accurate.  And for what it's worth, the specs on the XPS 17 9700, which has four TB3 ports, indicate that all of them only support DP 1.2 as well.
Short version:Can anyone who has an XPS 15 9500 with an NVIDIA GPU and the ability to connect an external display/TV to their system perform a quick test for me?  Connect the display to the non-Thunderbolt USB-C port on the right of the system, then open NVIDIA Control Panel and go to the PhysX Configuration page.  In there you'll see a diagram showing which GPU has direct control of each active display.  Which GPU is shown as having control of the external display you connected to that port?  And then if you move that display over to one of the Thunderbolt 3 ports on the left, which GPU shows as controlling it there?Background:The reason I'm asking is that the XPS 15 9500 specs indicate that the non-Thunderbolt USB-C port on the right supports DisplayPort 1.4.  To my knowledge, the Intel GPU built into the CPUs used by the XPS 15 9500 still only supports DisplayPort 1.2, since Intel hasn't upgraded the GPU on their H Series CPUs like they did for the "Ice Lake" CPUs found in systems like the XPS 13.  In that case, the only way DP 1.4 support would seem possible would be if the non-Thunderbolt port's GPU output was driven directly by the NVIDIA GPU instead of the Intel GPU -- but Dell historically has not wired USB-C/TB3 ports to the discrete GPU, even on systems here other outputs are wired that way, such as certain Alienware and Inspiron Gaming systems.  The only partial exception is the Precision 7000 Series models, which offer a BIOS option allowing you to choose which GPU controls the outputs.If the non-Thunderbolt port is wired to the NVIDIA GPU, that's good news since it opens up use cases like G-Sync, VR, and even DP 1.4-based 5K displays.  The only tradeoff is that using an external display connected to that port while on battery power would increase battery drain, since you now need to keep the NVIDIA GPU running whenever a display is attached there, even if nothing graphics-intensive is going on -- which is why most laptops wire display outputs to the Intel GPU, so the NVIDIA GPU can be shut down whenever nothing graphics-intensive is going on.But the question that would still leave open is what happens for XPS 15 9500 systems that don't include an NVIDIA GPU at all, which is an available configuration.  It would seem that either the non-Thunderbolt USB-C port would be limited to DP 1.2 or wouldn't support video output at all.  Either way, that would conflict with what's written in the specs (as of this writing).
Question for any XPS 15 9500 owner