Plugable UD-3900PDZ

Put the right screen on each output

The native HDMI connection is rated for 4K at 30Hz. The two DisplayLink connections suit 1080p screens at 60Hz. That arrangement is sensible for keeping chat, email, or a source document beside a main workspace. It is a poor reason to buy three identical 4K monitors: this dock cannot run all three at 4K.

Two prerequisites for three working monitors

Your laptop needs a video-capable USB-C port for the native screen, and permission to run DisplayLink for the other screens. On an employer-managed Mac, ask about software installation and the macOS Screen Recording permission before ordering. The permission enables display transport; it is not a claim that this dock saves your screen.

Count the connections you will leave plugged in

Six USB-A 5Gbps sockets give this model a practical role when a desk has several older peripherals. Its current specification lists 100W host charging. Compare that with your laptop’s power requirement separately from the monitor checklist, and retain the original charger if your workstation needs more.

Connections & compatibility

Connection to laptop

USB-C with DisplayPort Alt Mode and PD

Display technology

displaylink

Maximum displays (conditions apply)

3

Power to laptop (W)

100

HDMI sockets

3

DisplayPort sockets

0

Wired network

Gigabit Ethernet

USB peripherals

6 USB-A, 5Gbps

Display requirements

1 × 4K30 native Alt Mode; 2 × 1080p60 DisplayLink

Mac notes

DisplayLink installation required; Alt Mode needed for the native output

Windows notes

Windows with DisplayLink software; native channel also requires DP Alt Mode

These are published specifications, not results from hands-on testing. Maximum screen counts depend on the laptop, operating system, connection and chosen resolution.