New 'Thunderbolt' dock connects three 4K displays, with a catch

Plugable UD-6950PDZ publishableImage: Plugable

Clarification: Plugable sent us a statement after this story had been published. Technically, the UD-6950PDZ is not an official Thunderbolt dock. According to Plugable, the UD-6950PDZ is “is fully Thunderbolt compatible; it just doesn’t fully meet the Thunderbolt protocol set by Intel (the Thunderbolt trademark holder), which is why we can’t classify it as a Thunderbolt dock.” The original story follows below.

Plugable leads our list of the best Thunderbolt docks for your laptop precisely because the company focuses on the most important element: the display connectivity, with two 4K displays. But at CES, the company has upped its game: now there’s three!

The $219 Plugable UD-6950PDZ includes support for three 4K monitors, not just two. And in the spirit of Plugable docks, the company doesn’t make you choose between DisplayPort and HDMI connections: the UD-6950PDZ includes three of both.

The dock works with a standard USB-C connector on your laptop, but you’ll need an available Thunderbolt port (with Thunderbolt 4 preferred) to enable the full benefits. Unfortunately, the dock’s specifications hide a few gotchas, and answer the question of whether a Thunderbolt dock can accommodate three 4K displays. The answer? Yes, sort of.

Specifically, the UD-6950PDZ includes a pair of DisplayPort 1.2/HDMI 2.0 ports on the rear, which can output 3840×2160 video at 60Hz—the 4K60 output that’s expected of Thunderbolt docks. But the third port is HDMI 1.4/DisplayPort 2.0, and is limited to 3840×2160 resolution at 30Hz, instead. To be fair, 30Hz is acceptable for a secondary display used for static content like email or messaging apps, but staring at a 30Hz display for a prolonged period can strain your eyes.

But there’s another gotcha, too. Neither of the 60Hz DisplayPort/HDMI ports supports HDCP, which enables protected content (a Blu-ray disc, or Netflix, or Amazon Prime) to actually display on the screen. HDCP is listed as “host dependent” on the 30Hz port, instead. Simply put, you’re trading off a third display for limits on its frame rate and an overall restriction on HDCP playback. (To be fair, you’ll almost certainly be able to play back protected content on the laptop itself.)

Otherwise, though, there’s a lot to like with the UDZ-6950PDZ. The Thunderbolt connection back to the host can support 60W of power, covering a wide range of mainstream and thin-and-light devices. The dock also supports six USB-A ports (all at 5Gbps, with two to the front and four on the rear). If there’s any other weakness, it’s that there’s no USB-C output of any kind, so you won’t be able to add a USB-C dongle if you suddenly need an SD card slot, for example.

Plugable will ship the dock later this quarter, Plugable said.

As PCWorld’s senior editor, Mark focuses on Microsoft news and chip technology, among other beats. He has formerly written for PCMag, BYTE, Slashdot, eWEEK, and ReadWrite.

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