Difference of Image quality on dual monitor setup

[wlopes]

I just bought a new UD-3900PDZ to setup a dual monitor system. I installed 2 Dell S2722QC to the hub and I am using a MBP running displaylink 1.10.2. One monitor looks incredibly sharp and when I look at the monitor data it says it is receiving YCRB level signal. Meanwhile the second monitor looks a bit fuzzy and is receiving RGB level signal. If I connect any one of them alone they both look great.

[SamR]

Hi Will,

Thank you for contacting Plugable! I’m sorry the video quality of the screens connected to the UD-3900PDZ isn’t consistent, and I’ll be happy to help. Based on the information provided I’m not immediately sure why you’re seeing this issue, but I have a few questions to help clarify the situation further.

The three HDMI ports on UD-3900PDZ are labelled “HDMI 1”, “HDMI 2”, and “HDMI 3”:

The HDMI 1 port of this dock uses DP Alt mode from the connected computer for video, whereas the HDMI 2 and 3 ports use DisplayLink technology. The HDMI 1 port also supports a higher maximum resolution (4K 30Hz) compared to the HDMI 2 and 3 ports (1080p 60Hz).

Keeping this in mind:

• Can you please specify which HDMI port is producing clear images, and which one is producing fuzzy images?
• When you connect the monitors individually where they look normal, do you always use one specific HDMI port on the dock?

Can you also confirm if you’re using the USB-C cable that was originally included in the package with the dock? I ask because we’ve seen issues with other cables in the past.

Lastly, can you please specify the brand and model number of each monitor you’re using with the dock? This information is usually printed on the label on the back of each monitor.

Please let me know if you have any questions as well.

My apologies for the frustration, and thank you for giving us the chance to help.

Sam
Plugable Technologies

[wlopes]

Thank you for the quick reply Sam. I didn’t realize that each HDMI port supported different resolution/tech. I am using 2 Dell S2722QC monitors. When they are plugged into HDMI 1 it looks very sharp and when any of them are plugged into HDMI 2 & 3 it looks a bit fuzzy around the text. I guess based on your original response is that one is displaying 4K and the other not.

Do you sell a docking station that is capable of displaying 2 monitors at 4K?

[SamR]

Hi Will,

Yes, I agree that this is likely the result of one display being able to support the full 4K resolution where the other is being limited by the port it is connected to on the UD-3900PDZ.

As an alternative docking station which supports 4K 60Hz on both of its video outputs, I’d suggest UD-6950PDH: https://plugable.com/products/ud-6950pdh

UD-6950PDH is a DisplayLink-based docking station which would connect to your Mac using its included 1 meter USB-C cable, providing up to 100W to charge your Mac. It provides the ability to connect up to two 4K 60Hz displays to its two video output groups. Each video output group offers the choice of HDMI or DisplayPort. It also features five 5Gbps USB ports, an SD card reader, a MicroSD card reader, a wired Gigabit Ethernet port, and two 3.5mm analog audio jacks for input and output devices.

Some important notes on products that use DisplayLink technology:

• DisplayLink-based USB graphics adapters and docking stations are “virtual” devices where much of the heavy lifting is done by the host system’s CPU, and uses software to essentially emulate graphics hardware. As a result, this setup is best suited for office/productivity tasks, and isn’t meant for graphically-intensive applications like video streaming or gaming.
• It would be necessary to install the DisplayLink driver (available from the “Downloads” section of the product page linked above) on your computer. Please note that this means that you must administrative privileges on the computer.
• DisplayLink does not support the playback of high-bandwidth digital content protection (HDCP) such as Netflix, Hulu, Disney+, Amazon Prime video, etc.

Please let me know if you have any questions, and thank you for your patience.

Sam
Plugable Technologies

[slinke]

I have the same issue using the UD-ULTC4K and a MacBook Air M2. When I connect my main monitor to the HDMI 1 (Alt Mode) and the second monitor into either HDMI 2/3 (DisplayLink), I get the same resolution options but it shows “low resolution” next to several of them that work fine on the main monitor (2560x1440 preferred). 3840x2160 (4K) works on both however it’s way too small to use for work applications. Is there a software option to fix this? If not, is there a recommended replacement dock that addresses this?

[SamR]

Hi Steve,

Thank you for reaching out. I’m sorry to hear of this issue, and I’ll be happy to help!

2560x1440 is supported by UD-ULTC4K, however the DisplayLink Manager software has a quirk where you may need to change a setting within the software in order for the display to work at full fidelity.

To enable this resolution to work at full fidelity, please click on the DisplayLink Manager’s icon in the macOS menu bar (looks like two interlocked rectangles) to expand it. Once it’s expanded, check the box next to “Enable experimental 3008x and 2560x modes”:

This should allow 2560x1440 to work with out it showing as “low resolution”.

Please let me know if you have any more questions and I’ll be happy to help!

Sam
Plugable Technologies

[slinke]

Thank you for the advice. That worked!

Steve Linke
+1 619-253-2442