Question for any XPS 15 9500 owner

@nputer  The specs of the XPS 15 9500 specs here indicate that the non-Thunderbolt USB-C port on the right supports DisplayPort 1.4.  If that is accurate, then dual QHD from a regular WD19 would be possible.  The specs also indicate that the Thunderbolt ports on the left only support DisplayPort 1.2.  The only way I can account for this discrepancy would be if the TB ports were wired to the Intel GPU and the non-TB port was wired to the NVIDIA GPU.  The CPU in the XPS 15 9500 does not have the new GPU that Intel incorporated into the "Ice Lake" architecture used in CPUs like the ones in the more recent XPS 13 models.  They're still using a minor refresh of an older architecture, which includes an older GPU that only supports DP 1.2.  But the reason I'm a bit skeptical of the specs is because to my knowledge, this would be the first time that Dell has introduced a system with a USB-C/TB3 port wired directly to the discrete GPU.  The only semi-exception is the Precision 7000 Series models that have a BIOS option allowing you to choose which GPU controls them.

If the specs are accurate and the non-TB port is in fact wired to the NVIDIA GPU, then that's actually good news because it opens up use cases like VR and G-Sync that aren't possible when the display output is wired to the Intel GPU.  But even then, the specs would arguably require a bit of refinement, because the XPS 15 is available in configurations that do not include an NVIDIA GPU at all.  At that point the question becomes, what happens with the non-TB port?  Does it get wired to the Intel GPU, in which case it would only support DP 1.2 rather than 1.4, or does it not support video output at all?  The specs aren't clear on that, as of this writing.

I've asked an XPS 15 9500 owner via PM to test their ports to see which ports are wired to which GPU, but I haven't heard back yet. I'll follow up and post here if I find anything out.

Did you ever figure this out? I'd love to know the answer too.

@SUPERCILEX  Unfortunately the person I asked ended up returning their system before they got a chance to test.  I haven't yet spent the time to find and PM other people on this forum whose posts indicate that they own an XPS 15 9500 in order to ask them to run this test instead.  Given that the XPS 15 9500 comes with a USB-C to HDMI adapter, it would be very quick and easy to do this -- all they'd need is an HDMI cable and a display or TV with an HDMI input.

Bummer, thanks for investigating.

@Ray519  Thanks for sharing your results, even if the news isn't ideal.  It definitely sounds like you're dealing with DisplayPort 1.2 across the board.

To the point about DP 1.2 to HDMI 2.0 adapters being confusing since DP 1.2 can't run HDMI 2.0, the reason has to do with 4K 60 Hz.  The HDMI spec that precedes 2.0 is 1.4, but that can only run QHD 60 Hz or 4K 30 Hz.  In order to run 4K 60 Hz, the adapter has to support HDMI 2.0 -- although yes it's true that the HDR support also available under HDMI 2.0 isn't available from DP 1.2.  But that's the result of the reality that that there isn't a formal HDMI spec that describes the precise set of features that are and are not available from a DP 1.2 source.

All that said though, when using a straight USB-C to HDMI 2.0 cable or adapter, as opposed to something like a DA300 that tries to run USB 3.x alongside video, you should have been able to get 4K 60 Hz.  Did you confirm that you can send 4K 60 Hz to your TV on that particular input from another source (and using the same cable)?  The reason I ask is that some TVs have a Compatibility vs. Enhanced setting that has to be on their HDMI inputs, with only the latter setting allowing 4K 60 Hz, and that setting is often per-input.

But only being able to get 4K 30 Hz out of a DA300 would be expected when using a DP 1.2 source -- again, assuming the problem isn't elsewhere -- and inability to run dual QHD and USB 3.x over USB-C is also consistent with DP 1.2 rather than 1.4.

As of this writing, the Setup and Specifications documentation for the XPS 15 9500 still claims DP 1.4 support.  I've reported this to a Dell Support contact who's been good about routing these things internally to the correct teams, so hopefully that gets corrected.

Bummer, I really hoped that Dell had finally changed their GPU wiring design in order to allow things like DP 1.4, G-Sync, and VR from XPS systems.

So, my XPS 15 9500 just arrived and I also have not gotten it to work at DP 1.4 speeds on the right output.

Things I tried: connecting the included HDMI 2.0 Adapter (even more confusing if the device does not have the displayport support to actually run HDMI 2.0) to my TV: maxed out at 4K30. The Dell DA300 Adapter resulted in the same.

I have also been trying to daisy chain 2 QHD Monitors with USB 3.0 enabled, which failed. I could only run both monitors of one displayport, if the monitor limited itself to USB 2.0. At no point did the monitor show  an incoming HBR3 Signal, which would be the full bandwidth of DP1.4, which the U2520D is supposedly capable of, according to Dells specs.

@jphughan Yes, the TV runs 4k 60Hz 4:4:4 from my Desktop PC on the same input.

I was aware that a pure USB-C to Displayport / HDMI Adapter could achieve this also on DP 1.2. Just that labeling the included adapter as HDMI 2.0, to me, means that they not just made a typo with the DP version. Because even Dells own entry-level Laptops are listed with HDMI 1.4 even though they can output HDR, just at lesser resolutions or framerates.

Also, this makes the 9500 decidedly less capable out-of-the box than the previous version, which actually had a full-featured HDMI 2.0.

Just to be on the safe side I've now also confirmed the 3 monitor in total limit due to everything being run through the Intel UHD Graphics in practice, as well as no Gsync support.

Seemed more productive than being angry at Dell for lying in the specs.

Now I just need to decide whether to return my device over this...

@Ray519  I don't think the previous XPS 15 had a "full featured" HDMI 2.0 port.  The reason I say that is that the Intel GPU on that system controlled all outputs as well, and to my knowledge Intel GPUs still as of this writing do not support HDMI 2.0 natively.  Instead, systems that offer an HDMI 2.0 output as the previous XPS 15 advertised do so by feeding it with a DisplayPort 1.2 output off the GPU that gets converted to HDMI 2.0 internally.  This chip in at least some implementations is called an LSPCON.  And I seem to remember multiple users confirming that 4K 60 Hz with HDR was not possible from XPS 15 systems that had HDMI 2.0 ports.  So I don't think you've actually taken a step back.

HDMI 1.4 to my knowledge didn't have support for formal HDR standards (except Dolby Vision, which arrived later and was made backward compatible).  I realize that it would be able to transmit 10-bit color at lower resolutions, but that isn't technically the same as a formal standard like HDR10.  And DisplayPort 1.2 can also send a 10-bit signal at lower resolutions.

@Ray519  There was a very interesting post today in this thread indicating that on the XPS 17 9700, there is now a BIOS option to allow the discrete GPU to control the USB-C display outputs instead of the Intel GPU.  According to that post, you can do that by going the BIOS Setup, going to the Display section, scrolling down to "Direct Graphics Controller Direct Output Mode", and turning that On.  (That first "Direct" might have been intended to be "Discrete"; I'm just quoting from the person who wrote the post in that thread.)

Can you see if the XPS 15 9500 offers the same option?

Just rechecked with the latest BIOS (1.2.1 from today). No such option appeared for me.

Btw, I found Intel slides for 10th gen-H Processors that list the Display-Output Capabilities as DP 1.4 (HBR2). So this could explain how someone not knowing what HBR2 is, could have confused this and left it out of the specification.

@Ray519  Thanks for checking, bummer about that.  Do you have a link to those slides you mentioned?  I checked ark.intel.com for the CPUs in the XPS 15 and the max display resolution is still 4K 60 Hz, whereas the Gen 11 GPU in Ice Lake CPUs will do 5K (5120x2880).  I suppose they could have upgraded the GPU to support HBR3 purely to support higher-end daisy chain setups without increasing the max single display resolution, but I didn't see anything to indicate that when I last checked.  If the GPU does in fact support HBR3 though, then that begs the question of why the TB3 ports on the XPS 15 9500 and XPS 17 9700 only claim support for DisplayPort 1.2/HBR2.

I sure wish this information was easier to come by.  Even for products where HBR support level is well known, when explaining that as the underlying cause of some issue a person was having, I've had multiple people ask me, "Thanks, but how on earth was an average user supported to figure all this out?"  And I have to agree.

Please note: It explicitly says DP 1.4 (HBR2), so half bandwith compared to what one would normally understand 1.4 to support.

I've found these slides via Anandtech https://www.anandtech.com/show/15687/intel-details-10th-gen-comet-lake-h-for-45-w-notebooks-up-to-53-ghz for 10th-gen-H.

And https://www.anandtech.com/show/14256/intel-9th-gen-core-processors-all-the-desktop-and-mobile-45w-cpus-announced/2 for 9th-gen-H where it is still listed as DP 1.2.

I totally agree. I am usually the one asked about this stuff among my friends and actually try to read up on this and I still did not see this limitation coming...

@Ray519  Ugh, so DisplayPort 1.4 with HBR2 is a thing now?  This brave new world of standards where support for all sorts of useful features is optional is so irritating.  And I didn't even realize this combination was even allowed.  My understanding was that HBR3 was a REQUIRED part of DisplayPort 1.3.  Or maybe it was and Intel just decided to do their own thing because who's going to stop them?  So now I have to wonder what aspects of DisplayPort 1.4 actually ARE supported.  Formal support for HDR metadata?  DisplayPort DSC?  Actually I guess if DisplayPort DSC is supported, then that would substantially increase the display setups that could be run even on an HBR2 link, so long as you had displays that supported it.  An alternative might be an MST hub that supported it, and Cable Matters makes one, but it's not entirely clear to me right now if the MST hub can establish a DSC-enabled link with the system to allow a bunch more effective throughput and then "decompress" the stream for output to displays that don't support DSC, or if DSC support through the MST hub is only available in "passthrough" form, i.e. if the display itself supports it.  The former would of course be more useful, but it would also involve more complex electronics within the hub.

Anyhow, thanks for the link to those slides.  I had JUST started to enjoy that Dell was finally starting to indicate DisplayPort revision level support in the specs of their new XPS systems (a while after I raised that issue with Dell Support internally, though I'm not sure if there's a connection), and now Intel goes and makes this even more complicated.  As if taking two wildly different CPU architectures (Cannon Lake and Ice Lake) and calling both of them "Core 10th Gen" wasn't bad enough.