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WD19, two U2717D, Lenovo ThinkPad X1 Yoga, max resolution
Hello,
i have to address the community today because i think i can't see the forest for the trees anymore...
Today I bought a new DELL WD19 docking station to replace my old WD15. With this one I always had problems with the maximum resolution on my two monitors. At least I thought that the docking station is the problem.
My setup looks like this: Two Dell U2717D at the docking station and then the docking station via USB-C to my laptop. Unfortunately, this is not a Dell (company device), but a Lenovo ThinkPad X1 Yoga 3rd generation.
I would like to have all three screens (both Dell and the screen from the laptop) with a resolution of 2560x1440. Unfortunately I can't get that.
I have a desktop connected to the two Dells once via HDMI and once via DP and the resolution works. No problem at all. Therefore I assume that the monitors and all cables are ok...
In the company I also have two Dell monitors (unfortunately I forgot the model) which are connected via MST and the Lenovo laptop I can also simply connect to the primary monitor via USB-C. Here too, all three monitors work with the desired resolution. Therefore I assume that the laptop supports this config...
Now I'm trying all day to get it all done with my new WD19 and it just doesn't work. No matter how I wire it up I can only drive the built-in monitor and an external Dell monitor with the desired resolution. The second external monitor always gets a slightly lower resolution.
I suppose it's because of the bandwidth of the display port, but why does it work when I connect my desktop? One DP and one HDMI from the WD19 should give the same result, right?
Then there is the USB-C cable that connects the laptop. If this would be the bottleneck, it could not work in my company either...
I am a bit helpless. Could somebody explain it to me...?
Thanks a lot
Greeting
Johannes
jphughan
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October 8th, 2020 18:00
@johannesd The regular WD19 can only handle dual displays up to 2560x1440 each when paired with a system that supports DisplayPort 1.4/HBR3 over USB-C. The vast majority of systems on the market today are still limited to DisplayPort 1.2/HBR2 over USB-C, largely because most Intel CPUs on the market today still have GPUs limited to that level (and most laptops have the display output connectors wired to the Intel GPU even if they also have discrete GPUs.) That includes the CPUs available in your X1 Yoga Gen 3. When paired with a DisplayPort 1.2/HBR2 system, the WD19 is limited to dual displays up to 1920x1200 each or a single 2560x1440 display. This is explained in the Display Resolution Table section of the WD19 User Guide, available on support.dell.com.
However, you do sort of have a workaround here. Your X1 Yoga Gen 3 has USB-C ports that support Thunderbolt 3. As a result, if you were to get the Dell WD19TB, which uses Thunderbolt 3 rather than USB-C like the regular WD19, then you'll be able to run your desired setup. The WD19TB can tap into 4x more display bandwidth than the WD19 when paired with a DisplayPort 1.2/HBR2 system, so with the WD19TB you'd actually be able to run dual displays up to 4K 60 Hz each or triple displays up to 2560x1600 each.
jphughan
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October 8th, 2020 18:00
@johannesd Building on my reply just above, I realized I forgot to address your questions about why the other configurations work. The desktop works because it doesn't have to drive both displays over the bandwidth that's available over the USB-C link that the WD19 is using. As for the daisy chain, if you're plugging into a DisplayPort input on Display #1 there, then your USB-C interface has all four of its high speed lanes allocated to video bandwidth in that setup, which DOES allow enough bandwidth to run dual 2560x1440 displays even from a DisplayPort 1.2/HBR2 system. Or if you're plugging into a USB-C input on Display #1 and it's only trying to carry USB 2.0 traffic rather than USB 3.x traffic, then once again all four lanes in the USB-C link are allocated to video. The difference with the WD19 is that it's setting up the USB-C link to carry both video and USB 3.x. Carrying USB 3.x over USB-C requires two of those four high speed lanes, which means your available video bandwidth gets cut in half, from four lanes to two. I wrote a detailed explainer post about this here if you're curious, since this question comes up a lot.
DELL-Cares
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October 8th, 2020 01:00
We tried reaching you on a private message asking for the WD19 and U2717D Service Tag numbers. But did not receive a response. Please feel free to reply to the private message whenever you are available.
How to Use and Troubleshoot Dell Docking Station WD19
DELL-Cares
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October 8th, 2020 07:00
Thank you! We have received the required details. We will work the issue. You may also receive assistance or suggestions from the community members.
DELL-Jesse L
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October 8th, 2020 08:00
Read through this article to see if it helps =
How to Use and Troubleshoot Dell Docking Station WD19
In the company I also have two Dell monitors (unfortunately I forgot the model) which are connected via MST and the Lenovo laptop I can also simply connect to the primary monitor via USB-C. Here too, all three monitors work with the desired resolution. Therefore I assume that the laptop supports this config.
* Are you saying that this same Lenovo ThinkPad X1 Yoga is also taken to work?
* But at work you are NOT going through a WD19 dock. You are going straight from this very Lenovo ThinkPad X1 Yoga to two unknown Dell monitor and getting 2560x1440 60Hz on both and the laptop lid is open?
Lenovo ThinkPad X1 Yoga Thunderbolt 3/USB Type-C out port --> USB Type-C to C cable --> #1 unknown Dell monitor USB Type-C in port
#1 unknown Dell monitor DP out port --> DP to DP cable --> #2 unknown Dell monitor DP in port
Is the external AC power connected to the Lenovo ThinkPad X1 Yoga?
So in this setup =
Lenovo ThinkPad X1 Yoga Thunderbolt 3/USB Type-C out port --> WD19 USB Type-C connector cable
WD19 DP 1.4 out port --> U2717D DP to mDP cable --> #1 U2717D mDP in port
WD19 HDMI 2.0 out port --> HDMI to HDMI cable --> #2 U2717D HDMI in port
Close the laptop lid. Do the two U2727D monitors then work at 2560x1440 60Hz? If yes, then the fault may not be the dock or the monitors. The fault could be the laptop not providing enough bandwidth from its Thunderbolt 3/USB Type-C out port.
Have you also posted the issue on the Lenovo Forum to get their advice?
johannesd
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October 8th, 2020 23:00
Hello,
I have just checked it again. At my work it is as follows:
Two Dell U2719DC connected together via a display port cable. I selected USB-C as the source on the primary monitor and also connected it to the corresponding port on the laptop. This USB-C port is used to charge the laptop, control the monitors and the USB ports on the monitors.
Same laptop as the WD19 setup at my home.
Greeting
Johannes
jphughan
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October 9th, 2020 08:00
@johannesd The U2719DC has a "USB-C Prioritization" option. When you have a daisy chain set up, it defaults to "High Resolution", which means the USB-C link is set up with all four high speed lanes allocated to video, and only USB 2.0 data speeds (USB-C connectors include dedicated pins for USB 2.0). If you set that option to High Data Speed instead, then it will set up the USB-C link with only two high speed lanes allocated to video, plus USB 3.x data speeds. But the only way to run dual QHD/1440p 60 Hz displays from only two high speed lanes is with a source system that supports DisplayPort 1.4/HBR3. If you had a system like that, then this configuration would be ideal since you get your dual displays plus USB 3.x data speeds. But your system only supports DisplayPort 1.2/HBR2, so in order to run dual QHD/1440p 60 Hz from your system, you need to limit USB data speeds to USB 2.0, which means any devices you plug into the display's built-in USB ports will be limited to that speed, even though the display has USB 3.x ports.
The WD19 doesn't offer an option to set up the data link for four video lanes and only USB 2.0. It always runs USB 3.x, and therefore only two lanes for video. That plus the fact that your system only supports DP 1.2/HBR2 is why you're having this issue. But if you get a WD19TB, you'll be able to run your desired display setup (and even higher-end setups) plus USB 3.x.
johannesd
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October 10th, 2020 08:00