Compatibility with HP Spectre x360 15t (4HG39AV_1)


My experiences with the UD-ULTC4K and my new HP Spectre x360 15t (4HG39AV_1) laptop. This is a relatively new model with a six core Intel i7-8750H Coffee Lake processor.

Executive summary: looks good so far.

I wanted a three monitor solution that would work with the three monitors I have, but allow me to upgrade to additional QHD or UHD monitors in the future. I have:

HP EliteDisplay 27" E272q, 2560x1440 (QHD)
Samsung Syncmaster 24" 245bw, 1920x1200
HP LP2065 20", 1600x1200

I connected the E272q via HDMI, the other two monitors via DisplayPort-to-DVI dongles and DVI cables.

I downloaded and installed the DisplayLink drivers per the instructions that came with the UD-ULTC4K, then connected the laptop to the dock. I’ve now got all three monitors running at their native resolution, as well as the laptop internal UHD display, for a total of four displays.

It’s a little funky dragging a window back and forth from the laptop built-in UHD display to one of the other displays; since the laptop display is UHD (3840x2160), the window from the laptop initially appears huge on one of the other displays; however, Windows resizes the window to a sensible size as I continue to drag it.Same for dragging the other way; windows from the external monitors appear tiny when dragged to the laptop display, but Windows resizes it on the fly as I continue to drag it.

I’ve not yet had the laptop battery fall to a low level, but the dock has successfully charged my laptop over the USB-C host cable from 90% up to 100%. No messages about proprietary HP chargers being required or recommended; at least, not yet.

I have unplugged and re-plugged the laptop from the dock just a time or two so far, but each time, the Windows from all external monitors successfully relocate to the built-in display (on disconnect) and the external monitor layout configuration is successfully restored (on re-connect). The open windows do not relocate to the external monitors on which they previously were located, but I didn’t expect that.

I’m not really stressing the two DisplayPort connections; those monitors are relatively low resolution compared to the documented specs of those ports on this dock. I hope to upgrade at least one of those monitors in the future to at least QHD.

I haven’t finished migrating all my USB devices from my previous desktop system to the new dock, nor the wired ethernet connection, but I don’t expect any issues there.

Intended use is software development, including running one or more VMs, mostly while docked. I’m not a gamer so I can’t tell you whether this setup is good for that.


OK, more info.

Although the laptop seems functional while docked, and does seem to charge under certain circumstances, it seems that performance of the laptop is greatly curtailed when the only source of power is the dock.

I ran the Passmark benchmarking program several times in different configurations; each time the HP power supply was disconnected, all scores (CPU, 2D graphics, 3D graphics, memory, disk) were significantly lower. Although it was connected to dock power, which was maintaining the battery at 100%, it “knew” that it did not have full power available and apparently went into some sort of power-saving mode.

So, I’ll need to connect the HP power supply when doing resource-intensive work, but for just surfing and checking email, the dock power seems to work OK.


Hello, thanks for posting and for your detailed report! I am glad to hear that the dock works and we will be able to use this information to update our compatibility charts and product pages.

The DisplayLink DL-6950 chipset within the dock is not recommended for graphics intensive applications as it cannot deliver the same performance as a dedicated graphics adapter, which certainly explains the lower scores in Passmark. We generally only recommend our dock for office/productivity applications because of this.

The specs of this laptop states that it uses a 135W charger which explains why our dock is unable to supply a sufficient amount of power when preforming intensive tasks as it only offers 60W.

Thank you,

David W.
Plugable Technologies


FYI, I was curious if the HDMI port on the laptop itself was still live while docked, so for the fun of it I connected another monitor. It worked! So this laptop/dock combination has the capability to have four external 4K monitors, plus the internal UHD laptop display, for a total of five displays. That means that undocking would involve disconnecting three cables: USB from laptop to dock, laptop power, and this additional HDMI connection. I’m not likely to use it in that configuration any time soon, though.



Thanks for the reply. I was only sharing the Passmark data to illustrate the performance difference with and without the HPE power supply. I’m happy with the video performance of the dock for the tasks I’m going to be performing: software development, mostly text editing, running command line tools, and not-very-demanding GUIs like IDEs. No gaming.

An update on charging: I have now connected the laptop with 20% battery left to the dock without the HPE power brick, and it’s charging fine. I imagine if I started using the laptop intensely, I might be drawing more juice out than the dock could replace, and even quiescent, it’s probably not charging as fast as it would with the HPE charger, but the dock charging capability will be fine when I’m just too lazy to pull the power brick out of the computer bag at the end of the day.

Sorry if I may like a shill for this dock, but I’ve been really pleased so far.