USB docking stations such as the Plugable UD-3900 are neat because they allow you to connect additional monitors to your computer. The UD-3900 dock is particularly good because it works without having to fiddle around for too long to make it work!
You can connect up to two different types of monitors to the Plugable UD-3900 docking station at the same time so you can connect two HDMI monitor displays, two DVI monitors, two VGA monitors or any combination of those with a maximum resolution of 1920 x 1200 per monitor.
A DVI to VGA adapter is included so you can connect a VGA monitor using a standard VGA to VGA cable. While you can connect two DVI monitors to the UD-3900 dock, you will need to use a HDMI to DVI cable for the second monitor, which is not included.
When getting a HDMI to DVI cable, it's worth investing in a bidirectional HDMI to DVI cable because you'll be able to use this same cable to connect the dock to a HDMI monitor as well.
Don't get a HDMI to DisplayPort cable though because this type of cable only converts DisplayPort output to HDMI and not the other way.
If you want to connect to two HDMI monitors, you will need to get a HDMI Female to DVI Male adapter so you can connect it to the UD-3900 dock’s DVI output, using a HDMI to HDMI cable to connect the second HDMI monitor.
As far as ports, the Plugable UD-3900 dock has ports on the back and front of the unit, as well as a wide support base where the unit sits upright securely. The sides of the UD-3900 dock feature cooling vents.
You get two USB 3.0 ports, a headphone 3.5mm output socket and a microphone line-in. USB 3.0 ports are great although one downside is interference with 2.4Ghz wireless devices so if you plan to use a wireless keyboard and/or mouse, you will need to connect the receiver into a USB 2.0 port of the docking station.
On the other side of the Plugable UD-3900 docking station, you find the rest of the ports which include four USB 2.0 ports, Gigabit Ethernet, socket, DVI port, HDMI port, PC port and power input.
The included USB 3.0 Type-A to Type-B cable is 91 cm in length so it's under a meter long which is long enough for a desktop setup.
When connecting speakers or a pair of headphones to the 3.5mm audio output jack of the Plugable UD-3900 USB docking station, you will need to change the default audio output in Windows by going to the Sound menu, selecting the Playback tab and then setting the Plugable dock station as the default playback device.
Luckily, most TVs these days have an automatic screen display feature (JustScan mode) that automatically resizes the screen so it's just a matter of going to your TV's picture settings and looking for JustScan.
As far as adjusting the screen resolution of the TV monitor connected to the Plugable dock, you won't be able to use a graphics utility (i.e. Intel, Nvidia, or AMD/ATI), only the Windows Display screen resolution feature.
When using screen sharing and graphics editor applications such as Photoshop and Join.me on the TV monitor attached to the Plugable USB docking station, you will need to tweak your computer's internal graphics and in the case of Photoshop, you will need to disable "Use Graphic Processor" from Photoshop itself by unchecking the "Use Graphic Processor" tick mark  and then relaunching Photoshop.
When using Join.me on the monitor connected to the Plugable USB docking station, you will experience slowness because of the default rendering mode of your computer (desktop mode or angle mode).
The desktop mode uses OpenGL provided by the graphic card driver, while angle mode uses OpenGL ES 2.0 API on top of DirectX 11 or DirectX 9.
You will need to disable QT_OPENGL hardware acceleration by setting the QT_OPENGL value to "software" from the "Edit The System Environment Variables" menu.
If you cannot see QT_OPENGL as a user variable, you can easily create one by clicking new and entering QT_OPENGL as the variable name and "software" as the variable value. Software mode basically disables hardware acceleration and uses software-based OpenGL implementations.
While WQHD resolution is not 4k/ Ultra HD resolution (3840 x 2160), 1440p is a huge step up on 1080p Full HD so it's nice that the Plugable UD-3900 USB docking station supports Wide Quad HD (WQHD).
This means you can set a WQHD monitor to 1440p display resolution (2560 × 1440 pixels) in a 16:9 aspect ratio which is nice if you have a 27-inch TV monitor because you'll be able to see more information displayed on the screen at once (you can even fit two sizable browser windows side by side on the screen).
Saying this, 1440p display resolution will only be available if your HDMI monitor is a WQHD monitor or a HDMI monitor that natively supports 1440p (2560×1440) resolution. This important to know because some HDMI monitors that support even higher resolution (i.e. 2560×1600) do not support 1440p (2560×1440).
Also, the Plugable UD-3900 USB docking station can only handle 1440p display resolution at 50Hz refresh rate and when a single WQHD monitor is connected to the dock. You will also need to have the current DisplayLink docking station driver installed and use a High Speed HDMI cable for performance.
You cannot use a standard HDMI cable because it can only handle 10.2 Gbps of bandwidth. High Speed HDMI cables use the HDMI 2.0 specification (18Gbps of bandwidth) which can handle also 4K (Ultra HD) TV video signals at 60fps. If you want a docking station with 4K support, check out the UD-5900 dock.
Something else you will also need to tweak, if you are using a laptop, is the power management settings because when you hook the Plugable UD-3900 docking station to your laptop/multi-monitor setup and close the laptop lid, the monitors connected to the dock will power off, shutting down the laptop.
Simply go to "Choose what closing the lid does" under the ‘Plugged In’ column in Power Options and set it to "Do Nothing".