Possibly, but with some limitations. Assuming a fully compatible computer with USB Type-C DisplayPort Alternate Mode 1.4 (or better) and DSC (Display Stream Compression) then three 4K displays will most likely work, but with one or two displays limited to 30Hz refresh rate.
| DP 1.4 DSC Ratio 3:1 | DP 1.4 DSC Ratio 2.4:1 | |
|---|---|---|
| Single Display | 4K 60Hz | 4K 60Hz |
| Dual Displays | 2x 4K 60Hz | 2x 4K 60Hz |
| Triple Displays | 2x 4K 60Hz 1x 4K 30Hz |
1x 4K 60Hz 2x 4K 30Hz |
| This table assumes: 1) A host computer with USB Type-C DisplayPort Alternate Mode version 1.4 with Display Stream Compression (DSC) enabled 2) All 4K displays support both 30Hz and 60Hz refresh rates. Not all computers or displays will meet these criteria. | ||
Why the limitation
There just isn't quite enough bandwidth for a USB Type-C port with DP 1.4 and DSC to enable three 4K 60Hz displays, however with a DSC compression ratio of 3:1 two 4K 60Hz displays and one 4K 30Hz display should work.
However, there is a bit of a wrinkle, DSC compression ratios are not set in stone, some computers enable 2.4:1, which can only support one 4K 60Hz display and two 4K 30Hz displays.
The operating system is not made aware of any of these settings, it won't report the DisplayPort Version (1.2, 1.4, 2.0 etc), nor will it report if DSC is available, or the DSC compression ratio. Often the system manufacturer will include the DisplayPort version, but not DSC or compression ratios in the system specifications or user manual. The only way to know for sure is to try.
Additionally, since this is not an operating controlled setting, changing the resolution in Windows or ChromeOS settings will not change the display refresh rate. For example with three 4K displays connected to a USB Type-C DP 1.4 DSC Ratio 2.4:1 host computer, setting the two 30Hz displays to 1080P in Windows Settings will not enable 60Hz refresh rate. While the output resolution has been reduced, the display signal is still transmitting at 4K 30Hz.
What does 30Hz refresh rate mean?
The refresh rate, measured in hertz (Hz), is how many times the display is updated per second. Historically, computer displays have a 60Hz refresh rate in North America as the refresh rate was originally based on the grid power frequency. This legacy has carried on to digital computer displays and is the most common display refresh rate in North America.
At 30Hz refresh rate the display updates once for every two updates of a 60Hz display. The mouse and keyboard can feel a bit sluggish on a 30Hz refresh rate display, animations may seem a bit choppy, but most video playback will be unaffected - video is often recorded at 30fps, and static images will appear just fine.
Why isn't Plugable recommending three 4K displays with this docking station?
We find 4K 30Hz refresh rate displays to be just a bit distracting, it isn't optimal, and it is difficult to understand without experiencing using a 30Hz display. There is also a lack of information from system manufacturers and from the system itself about the USB Type-C port capabilities, where there more transparency here we could better judge how any system would enable three 4K displays, however as it is we are choosing to be cautious with the display support to ensure that this docking station can deliver exactly what is promised.
If you are unsure if your computer, displays, or setup are compatible with this docking station, or if you have any additional questions please contact our support team at support@plugable.com, we are happy to help!
