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Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?


@decker12 wrote:

Well, good news is that the DP to USB-C cable I bought works.

Bad news is that HDMI from the monitor to HDMI on the Dock doesn't work at all when I plug that DP to USB-C cable into the WD19TB dock. It simply isn't recognized when I have the DP to USB-C cable plugged in on the 2nd monitor. Unplugging that DP to USB-C cable makes the HDMI monitor instantly light up.

What does work is if I use a HDMI to USB-C cable and plug that into the TB3 port on the back of the "side addon" piece of the WD19. Then both monitors lit up at 4k and 60hz. I will have the user dock, undock, put it to sleep, etc in an effort to make sure they always wake up at 4k and 60hz instead of reverting to some other resolution or 29hz.

So, in summary:

  • Monitor 1 HDMI to Dock HDMI, Monitor 2 DP to Dock DP
    • Only DP Monitor 2 works
  • Monitor 1 DP to Dock DP, Monitor 2 DP to Dock DP
    • Both monitors stuck at 4k 30hz
  • Monitor 1 using HDMI to USB-C Adapter to Dock TB3 port in back, Monitor 2 using DP to USB-C Adapter to Dock USB-C "DP" port on back
    • Both monitors work 4k at 60hz

Anyway, I'll know more in a few days as the user puts the WD19 through it's paces.

Do you know if this WD19 fixes the 2.4ghz interference issue that happens from the dock's USB3 ports? That was a problem on the TB16 and it also exists on most of the 3rd party TB3 docks I've tried. 


@decker12 thanks for the connectivity tips, that's quite handy to know that is exactly what is required to get the dual 4k display at 60hz. I'll keep that noted as the documentation isn't too clear when it advises of this.

2.4ghz interference issues - I have searched all of our articles related to the TB16 and not one of them mentions this interference. Can you provide more information on this problem please so I can investigate it further.

Alan

DELL-AlanD
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#IWork4Dell
I'm based in the UK and I'm usually available Monday to Friday 9am-4pm GMT
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decker12
2 Iron

Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?

Here's the article on 2.4hz interference with USB3 docking stations:

https://www.intel.com/content/www/us/en/products/docs/io/universal-serial-bus/usb3-frequency-interfe...

We've seen this time and again on all of our TB16s. The end result is that the typical Logitech wireless keyboard skips key, and the mouse "stutters" while you're moving it around. It's infuriating 🙂

The fix for the TB16s was to install a USB2 hub (AmazonBasics 3 port hub for $10 worked fine), and then plug all 2.4ghz devices into that hub. That put just enough distance between the TB16 and the wireless devices to solve the problem. It was however a huge headache at the time trying to figure out what the issue was.

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decker12
2 Iron

Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?

Frustratingly, my user who's testing out the WD19TB for us just reported that he plugged in his 7490 via TB3 and one of his 4k monitor simply wouldn't go above 1080p. Display properties didn't have anything above 1080p as an option.

The cable he was using as a HDMI (monitor) to USB-C (plugged into the back of the dock). I had to physically unplug the HDMI cable on the back of his monitor and replug it back in for the monitor to wake back up and allow it to go to 4k.

Obviously I can't have users screwing with unplugging cables behind their monitors every day when they come into work, so we'll have to wait and see if this problem is one that goes away.

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Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?


@decker12 wrote:

Frustratingly, my user who's testing out the WD19TB for us just reported that he plugged in his 7490 via TB3 and one of his 4k monitor simply wouldn't go above 1080p. Display properties didn't have anything above 1080p as an option.

The cable he was using as a HDMI (monitor) to USB-C (plugged into the back of the dock). I had to physically unplug the HDMI cable on the back of his monitor and replug it back in for the monitor to wake back up and allow it to go to 4k.

Obviously I can't have users screwing with unplugging cables behind their monitors every day when they come into work, so we'll have to wait and see if this problem is one that goes away.


@decker12 thanks for this additional info. I agree with you that having the end users have to do that is not how you would expect it to work. My concern is that this is a scenario or configuration that we have not encountered during testing and development and that I may need to raise it to engineering for further investigation. 

Before I can do that they will require a troubleshooting to be exhausted first before it gets escalated. I would recommend running through the troubleshooting steps for the WD19TB as per this article. It goes through the multiple different monitor configurations / connection types etc. 

https://www.dell.com/support/article/us/en/04/sln316830/how-to-use-and-troubleshoot-dell-thunderbolt...

I hope this helps and I look forward to hearing how you get on.

Alan

DELL-AlanD
Social Media Support
#IWork4Dell
I'm based in the UK and I'm usually available Monday to Friday 9am-4pm GMT
Get Support on Twitter @DellCaresPro

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decker12
2 Iron

Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?

User reported that both monitors came up properly at 4k this morning when plugging in the TB3 cable. The difference today is that he kept his laptop lid closed, so Windows detected two display devices (4k LG + 4k LG) instead of three (4k LG + 4k LG + Laptop screen).

The user reported that he did not need to push the power button on the Dock to wake his computer out of sleep and bring up the monitors. Just taking his sleeping laptop out of his laptop bag, and plugging in the cable was enough to do that, which I found a bit odd.

Anyway I'm going to keep an eye on this for another couple of days to see if he has any more unusual behavior.

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jphughan
5 Tungsten

Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?

I went on vacation for a week so I've missed this until now, but dual 4K 60 Hz from a WD19TB is possible if two conditions are satisfied.  First, the 7490 must have Thunderbolt 3, which is optional on the 7490.  Otherwise, the WD19TB will operate in USB-C backward compatibility mode, with the bandwidth limitations that entails, which on an HBR2 machine like the 7490 means dual displays only up to 1920x1200 at 60 Hz.  And second, one of the displays needs to be connected to the USB-C "upstream" port on the back of the dock.  This is all specified in the WD19TB manual, fyi, and I wrote a detailed thread about the display configuration limits of the WD19 family, including that port restriction for 4K 60 Hz, this thread if you're curious.

On the subject of that "upstream" USB-C port, whenever possible I recommend using USB-C to DisplayPort adapters/cables rather than USB-C to HDMI, for several reasons:

- All cables/adapters of former type will handle at least 4K 60 Hz, whereas only USB-C to HDMI 2.0 cables will handle the latter.  There are USB-C to HDMI 1.4 cables that might only do 1440p, for example.

- USB-C outputs provide a native DisplayPort signal anyway, which means USB-C to HDMI cables/adapters have to include a chip to actively convert that DisplayPort source signal to HDMI.  That's usually additional cost and always additional complexity.

- Some older 4K 60 Hz displays only accept 4K 60 Hz over their DisplayPort inputs anyway, because 4K 60 Hz only arrived with HDMI 2.0, which didn't arrive for quite a while after DisplayPort 1.2.

jphughan
5 Tungsten

Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?


@jimaah wrote:

Dual 4K 60Hz is not possible through the DisplayPort outputs on the Dell WD19TB dock. This I find odd to say the least as it's a step backwards from the older Dell TB16 dock with which you could get dual 4K 60 Hz via the DisplayPort outputs.

To get dual 4K 60Hz you'll either need to:

  1. Buy a notebook that supports HBR3 (very niche right now)
  2. Buy a USB-C to DP adapter to workaround this (your mileage may vary)
  3. Buy a dock that supports dual 4K 60Hz without needing to do 1. or 2. such as the Dell D6000 https://www.dell.com/en-us/shop/dell-universal-dock-d6000/apd/452-bcyt/pc-accessories

 


@jimaah  I agree that the port restriction on dual 4K 60 Hz seems odd, especially given that it didn't exist on the TB16, which is partly why I wrote the thread I linked in my post above to explain what's going on.  Your alternative options are all correct, but it's worth pointing out that the D6000 option carries a lot of other ramifications.  First, it will limit you to 60W charging, whereas the WD19 family can supply 90-130W depending on the system and the AC adapter wattage driving the dock itself.  And second, the D6000 uses a DisplayLink chip rather than native GPU output, which has a LOT of potential drawbacks that might affect people's use cases.  I wrote about those in this thread, specifically the post marked as the answer.  So yes, it might be a viable option for some, but that option should include some asterisks when it's mentioned.

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jphughan
5 Tungsten

Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?

@decker12  if your displays support HDR, then you wouldn't be able to run that color space with both 4K and 60 Hz also in use, because the bandwidth requirements of that setup exceeds a full DisplayPort 1.2 channel's capacity, and the 7490 only supports DisplayPort 1.2 (HBR2) output.  Some displays claim HDR support by deriving a faux HDR signal from an SDR signal, but if your display supports the actual HDR10 standard, then you'd need to either reduce your resolution or refresh rate to send it.  I suppose you could also reduce the chroma subsampling from the default 4:4:4 to something like 4:2:2 or 4:2:0, but I don't know if that option is implemented anywhere.

As for the cable length and power requirements question, I was actually curious when I read the WD19TB's specs indicating that the cable was now 0.8 m.  At first I thought it might have been an error in the documentation, but if you're finding that it is in fact longer than the TB16's, I guess there might have been advances in passive cable technology in the 4 years since the recalled TB15 (which was the basis for a slightly modified TB16) and today's WD19TB model.

decker12
2 Iron

Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?

@jphughan Thanks for that post! It was very helpful and increased my understanding of the WD19TB's output capabilities.

We're running it fine as your post and the manual recommended - HDMI to USB-C in the USB-C "Displayport" labeled port on the back of the WD19TB, and then a DP to USB-C plugged into the TB3 port on the back of the dock.

As soon as we ran that setup, both monitors lit up at 4k and 60hz.

As I posted earlier today, the only snag we saw in the past couple of days was that the user couldn't get one monitor out of 1080p when he plugged in with his laptop lid open. Windows 10 just didn't see anything higher than 1080p as an option unless I unplugged the HDMI cable from the monitor and plugged it back in, at which point it immediately went to 4k.

When the user came in today and plugged in with the laptop closed, both monitors lit up at 4k 60hz without a problem.

So far I'm tentatively optimistic that the right combination of cables and the WD19TB dock is going to be the solution to my multi monitor problem that the TB16 dock did not solve. I just hope the WD19TB is more reliable - as I said, I have a stack of six or seven TB16s that I'm going to e-waste because they've all died on me for one reason or another.

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decker12
2 Iron

Re: WD19TB - 7490 - Dual 4k at 60hz - Impossible?

Unfortunately, the user has just reported the switch to 1080 on one monitor happening again. He unplugged his laptop, went to a meeting, came back with a closed laptop, plugged it into the dock, and 1 monitor popped up at 4k 60hz and the other popped up at 1080p without any option in the display settings to change it to 4k. 

This is how the user got it working again without having to unplug the HDMI cable from the back of the monitor, and it's a doozy. Something we definitely don't want our users having to do every time:

1) unplug dock, 2) open laptop screen, 3) close laptop screen (so it goes to sleep), 4) plug back in, 5) manually change resolution on monitor 2

I'm going to replace that HDMI to USB-C cable with another DP to USB-C cable to see if that fixes it. If not, I'm going to unfortunately have to return and write off our WD19TBs as we can't have our users screwing around like above when this problem happens. Sadly then I won't have any dual 4k docking solution. 

This is a one month old, all updated, 7490 with TB3 and Windows 10 so it's pretty close to out of the box. Monitors are also brand new.

I have thought it had something to do with the monitors, however we have several of the same monitors connecting to Macbook Pros using Caldigit TS3+ docks and those work fine at 4k and 60hz.

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