UD-ULTC4K DisplayLink issues with Acer XB321HK G-Sync monitors

OK, this one should be fun! I’m having an issue with connecting the DisplayPort ports directly to my monitors. The HDMI port runs fine at 4K, which means the DisplayPort alt-mode is working, and the laptop charges, which is fantastic. The issue is just with the DIspayPort outputs, which go through DisplayLink. I’ve seen the same issue with a number of products, which makes me think that the issue may be with some DisplayLink chips and either this monitor specifically or with G-Sync in general.

Equipment: Dell E7480 laptop, three Acer XB321HK, Windows 10.

Works: DisplayPort -> HDMI (passive adapter), gives 4K on all three monitors.
Works: DisplayPort -> HDMI (passive adapter) -> DisplayPort (active adapter) = 4K. Expensive way to go with the extra adapter, and a bit crazy with the double conversion, but it actually works.
DOESN’T work: DisplayPort direct to the monitor. Not just a black screen - the monitor doesn’t even show up in Device Manager.

Note that the Plugable UGA-4KDP USB-A to DisplayPort 4K adapter works fine with this monitor, but USB-A to DisplayPort 4K adapters from other manufacturers do not.

Any ideas on where to start? HDMI has certain advantages for me, so I can stay with that, but I’d love to figure out how to get DisplayPort working without the extra active adapter.

Hello, thanks for posting and I’ll be happy to help.

The behavior you describe sounds similar to what we have seen with some of our other DisplayLink based devices with the DL-6950 chipset within the dock and G-Sync enabled displays, but we’ve not specifically seen this manifest with the UD-ULTC4K dock yet. We’ve actually called G-Sync monitors and the same monitor you have on our UD-6950 dock’s page (https://www.amazon.com/dp/B075DJMVW2/) and it appears that the same affects the chip within the UD-ULTC4K. We’ve never had reports nor do we have these monitors to test internally but now we’ll be updating our pages to reflect this incompatibility when using DisplayPort to DisplayPort connections.

The UGA-4KDP adapter is based off of a different DisplayLink chipset (DL-5500) which may help explain why it works.

We can certainly send you our DisplayPort to HDMI active adapters (https://www.amazon.com/dp/B00S0C7QO8) or provide a partial refund to your order to cover the costs of these adapters in order for the three display setup to work for you. If interested, we will contact you directly to facilitate this process.

Thank you,

David W.
Plugable Technologies

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