New Dell XPS 15 9500 How to output 4K @ 60Hz HDR?

@juanjosedag  You can't.  4K 60 Hz HDR requires DisplayPort 1.4, and despite the XPS 15 9500 specs as of this writing incorrectly claiming that the regular USB-C (non-TB) port on the right supports DisplayPort 1.4, it doesn't.  It's limited to DisplayPort 1.2, because just like the TB3 ports on the left, its video output is wired to the Intel GPU, and the Intel GPU built into the CPUs used on the XPS 15 9500 only support DisplayPort 1.2.  That doesn't give you enough bandwidth for 4K 60 Hz with HDR unless you run reduced chroma, but I don't know if Intel GPUs support that.  DP 1.4 offers more bandwidth and can therefore run 4K 60 HDR with full chroma, but the Intel GPU in that system doesn't support that, and since the NVIDIA GPU isn't directly wired to any of the display outputs, its capabilities aren't relevant in this context even if you have an XPS 15 build that has an NVIDIA GPU.  (The NVIDIA GPU can still accelerate content because it operates as a render-only device using a technology called NVIDIA Optimus when needed, but since it always has to pass content through an Intel GPU to get out to a display, the capabilities of the Intel GPU impose limitations.)

@juanjosedag  One quick follow-up to the above.  The adapter that's included is supposed to support HDMI 2.0, which means even when it's being fed by a DP 1.2 source signal, it should run 4K 60 Hz without HDR, not 4K 30 Hz without HDR.  If you're having an issue there, make sure you're using an HDMI cable specifically rated for HDMI 2.0, which will typically be marked on the jacket as HDMI 2.0, or High Speed, or 18 Gbps.  If you've verified that the HDMI cable you're testing runs 4K 60 Hz from another source, then some TVs require you to put specific HDMI inputs into "Enhanced / High Speed" mode to support HDMI 2.0 signal types, so here again make sure that you've confirmed that the specific input you're using can accept 4K 60 Hz from another source, or go look for that type of setting.  If you're using a confirmed 4K 60 Hz cable with a confirmed 4K 60 Hz input, then I'm not sure what to suggest next.  Maybe trying another cable or adapter anyway?  The reason I say that is that I've seen multiple cases here where people reported USB-C to HDMI adapters not working with certain laptops, even though they'd confirmed that the adapter worked fine with other systems/devices.  And in those cases, trying another brand of adapter resolved the issue, in that the replacement worked with all of their devices.  Of course there's no GOOD reason that the first adapter shouldn't have worked the same way, but unfortunately not everything that SHOULD work in the tech world always DOES work.  In the case of USB-C to HDMI adapters, they need to incorporate an active signal converter chip to switch the DisplayPort signal coming from the system over to HDMI, and it seems that chip can be the source of some weird interoperability issues.  (This incidentally is why I recommend USB-C to DisplayPort adapters/cables whenever feasible, since in that case the system's native signal is being passed through as-is.)

@juanjosedag  Nice work on the testing!  I admit that I didn't think of the 8-bit with dithering option, although I'm not sure I would have considered that real HDR anyway.  And the DisplayPort 1.2 spec doesn't have formal support for HDR metadata for HDR10, HLG, and Dolby Vision as DisplayPort 1.4 does, although whether that matters to people will vary from person to person.

I'm a bit curious about how that DA20 adapter works, though.  It claims to support 4K 60 Hz as well as USB 3.x.  I also see that it's bundled with some other systems, namely the XPS 17 9700 and then the Precision sister systems of both of those XPS models.  On a system that supported DisplayPort 1.4, such as the XPS 17 9700 when the BIOS option to give the NVIDIA GPU direct control of the outputs is enabled (and which is apparently only available with the RTX GPUs, not the GTX GPUs), then running 4K 60 Hz and USB 3.x simultaneously would be possible.  But that isn't the case with a DisplayPort 1.2 system.  Based on your spreadsheet, it seems to limit itself to 4K 30 Hz when used with a DP 1.2 system.  That would match the behavior of the DA300 when paired with such systems, although in that case, given that the XPS 15 9500 is only capable of DP 1.2, I personally consider it misleading to claim that the XPS 15 9500 comes with an "HDMI 2.0 adapter" if that adapter can't actually be used for HDMI 2.0 output when paired with the system you're bundling it with.  I was hoping the adapter would be designed to limit USB data speeds to USB 2.0 if you were running HDMI 2.0, but that might not be practical given how USB-C link negotiations work, and limiting USB speeds to 2.0 all the time would certainly be annoying to other users who might want USB 3.x but wouldn't need 4K 60 Hz.

@juanjosedag  I was looking more into this DA20 adapter, and I found this Reddit thread.  The OP says that they're able to get 4K 60 Hz through that adapter even when using the Intel GPU, which only supports DP 1.2.  Given that the Intel GPUs in the XPS 15 and XPS 17 are the same because they use the same CPUs, that would suggest that this DA20 adapter may indeed be able to run 4K 60 Hz even from a DP 1.2 source, possibly by limiting USB data speeds (or perhaps only when no USB device is attached at all?)  But that conflicts with the results you posted.  Very strange....

@jphughan I was able to figure out this issue and registered my findings in this spreadsheet:

https://docs.google.com/spreadsheets/d/1A1KKLfCDwowODF7cinnvxecnagUyj7XjYeer7dfludA/edit?usp=sharing

These are my conclusions:

• It's possible to get 4K@60Hz HDR (8-Bit with dithering) output from the XPS 9500
• It's possible to get 4K@30Hz HDR (10-Bit) output from the XPS 9500
• The in-box adapter is pretty limited and will not go above 4K@30Hz
• Using an adapter with USB Hub will halve the Display Refresh Speed (you mentioned this before). If you want 4K @60Hz an adapter with only HDMI/DP should be used.

I ran these tests using the ports on the left of the XPS 9500.

I own the model with the NVIDIA card, and I had the same problem (4K @ 30 Hz only - HDR was not a concern for me), and therefore contacted Dell’s support.

Result after several phone calls and mail exchange:
- the Dell DA20 adapter, which was included with the laptop, does support 4K @ 30 Hz only
- Dell sent me another adapter (free of charge) – Dell 625RG – it’s label mentions “USB-C to HDMI (2.0)”
- this adapter supports 4K @ 60 Hz and works on all USB-C ports

After some initial frustration with the issue I am a happy customer now!

Any insight on how you were able to get the 625RG adapter for free? Did you call sales or technical support?

I call technical support and they were a complete waste of time. The rep keep asking about driver, and software. I told them it's not that but they kept insisting. Then, suddenly, the rep hung up. That happened twice. Finally, I got a rep that actually listened. But, she couldn't offer any solution other than for me to buy the adaptor myself. This is the worst support for any product I've ever had.