Precision 5530 + WD19TB - 4K 60Hz possible via HDMI?

@elroyh  That should indeed be possible as long as it’s the only active display. Initially while reading I thought the limitation might be the HDMI cable or the HDMI input on the display, since not all cables and inputs support HDMI 2.0, and early 4K 60 Hz that predated HDMI 2.0 would only accept that on DisplayPort, but if the same cable and display-side input can handle 60 Hz when connected to the system’s built-in HDMI output, that rules those issues out. If you haven’t already, update the system’s BIOS and Intel Graphics driver, and then also update the WD19TB firmware.

Just out of curiosity, why are you trying to switch to HDMI in the first place? Are you expecting to gain something that you don’t currently have when using DisplayPort?

@elroyh  Sorry, missed your last sentence that drivers and firmware were all current. In that case, the only admittedly long shot suggestion I’d have would be to try power cycling the dock so that it starts with the display already on HDMI, then dock your system. I doubt that’ll make a difference, but what you’re already doing should be working and obviously isn’t, so maybe doing something that shouldn’t make a difference actually will.

@jphughan Hi, Thanks for your reply...

Dell support are claiming that it is a processor limitation, which if it is then it'll be a limitation that applies to ALL Dell laptops that use up to 10th gen i9 processors. I don't quite get that - why spend money on a device with an NVIDIA Quadro GPU if it doesn't add any value in this scenario...

To answer your question - I am not switching to HDMI. I've invested in a 2nd of these WD19TB's. The first uses a DP cable and works fine, but when I tested the 2nd unit I could only initially do so with HDMI. I then also tested the first using HDMI and it produced the same results. That test also negates your recommendation of a WD19TB reboot I think...

The WD19TB documentation clearly indicates that 4K@60Hz is possible for both single and dual display configurations with the lower HBR2/DP1.2 bandwidth (which the Precision 5530 provides) but that clearly does not work.

So my question is why Dell would lie about that specification in their documentation?
Surely they don't need to sell their products under false pretenses???

@elroyh  I wouldn't go so far as to call it a "lie".  That suggests intent to deceive, and I don't believe that's what's happening here. That said, calling it a processor limitation is utterly wrong, for a few reasons.  First, it's clearly possible to run 4K 60 Hz off the system's built-in HDMI output, which is controlled by the Intel GPU just like the USB-C/TB3 port.  And second, when connected through the WD19TB, the system always uses DisplayPort to send video data to the dock regardless of the output you're using, because that's the only video protocol that Thunderbolt supports carrying.  If you use HDMI on the WD19TB, then a signal converter chip in the dock switches the received DisplayPort stream over to HDMI.  But the system itself doesn't operate any differently based on the dock output you use.  And lastly, I've definitely seen users run 4K 60 Hz displays via HDMI on their WD19TB units.  So worst case this may be an interoperability issue with this specific combination of hardware, or maybe even the current combination of latest firmware and driver releases, that's creating a limitation that shouldn't exist but does anyway -- not a case of Dell knowingly having a limitation here and lying about the dock's capabilities on their specs.  Similarly, the claim that this is a CPU limitation may have been due to a Dell Support rep misunderstanding something they read.  I've seen threads here from people who have been told some pretty bizarre things by Dell Support, including that systems can only run 4K external displays if they have 4K built-in displays and that the XPS 13 is such a high-end system that it can only run external displays through a full dock, not simple USB-C to DP/HDMI adapters.  The latter came up because somebody was having trouble with that case, which turned out to be because Dell had released a buggy BIOS update, and was fixed by yet another BIOS update issued months later.  It seems Dell Support reps can't or won't ever say, "I don't know."  So maybe if they can't solve the issue they're expected to just explain why it's unsolvable?

As for the NVIDIA GPU and the system's design, wiring all outputs to the Intel GPU is a pretty common design on systems that optimize mostly for battery life.  I wrote an explainer post on the various hybrid graphics designs and their pros and cons in the post marked as the answer here if you're curious.

@jphughan So I ask for assistance and the only response that is given is that it's not possible because of the CPU. Stated twice (after I questioned its accuracy) and confirmed a third time by the agent's "supervisor".
That that level of support is an indictment on Dell and completely disrespectful to those that have chosen to spend their hard-earned money on top-end Dell laptops and peripherals. It's disgraceful IMO.

Thanks for your detailed explanation once again. I was not aware of that technical detail but it makes sense, thanks. I'll definitely have a read of the post that you've linked...

Some of those other support responses are hilarious... Where would that leave a user that is not technical, for example. Laughable support offering if that is the output...

Let's hope that Dell are able to prove themselves by solving the problem.

@jphughan 
Your thoughts on swopping out the HDMI cable are worth investigating, thanks once again.
I'd think that the cable has shown that it can carry the load, but I hear your comments re chipsets, etc.
I may grab one 8K cable for testing and then probably switch to DP for the 2nd setup as well...

Latest response from Dell Support:
I see that you're working with our community on this...
I am hoping that you will find a solution soon.

@jphughan 
Hi,

So I went ahead and ordered a replacement HDMI 2.1 cable (rated/claimed 48Gbps and 8K/60Hz) and that seems to yield the full 4K/60Hz resolution via HDMI now.

Still interesting that my previous HDMI 2.0 4K cable worked perfectly via the laptop HDMI port but was not good enough for the WD19TB...

So thank-you very much for offering that advice - much better than Dell Support ever considered...
Hopefully someone else finds this useful as well.

@elroyh  Thanks for reporting back, especially with such great news!  I admit that I almost didn't even bother to suggest it since it seemed like a long shot, but then again when there are no obvious variables that can be changed or should have to be changed to resolve an issue that shouldn't exist, sometimes long shot ideas are the key.  Glad to hear you're good to go now.