We often get asked which HDMI splitter can be used to connect two monitors to one PC at the same time. In principle, this works with any of our HDMI splitters or HDMI matrix switches . Both screens display the same image. In the PC world, this is called " mirror mode ." What will never work, however, is using an " extended desktop ." In such a dual-monitor environment, each monitor shows a different part of the desktop menu. The workspace is doubled - a great thing. Unfortunately, this isn't possible with just one HDMI output on the computer. A splitter won't help either. A splitter only distributes the incoming signal and always delivers the same image at the outputs. 
But how else does it work? There are numerous installations with two monitors that display a different image! This is because an HDMI connection doesn't support the necessary "Multi-Stream Transport" (MST). Only DisplayPort and USB-C "Alternate Mode" or "Thunderbolt" ports on the computer support this. Therefore, displaying an extended desktop via HDMI is only possible if the graphics card already has two HDMI outputs, or if the computer has a DisplayPort port that supports MST. It also works if the computer has a USB-C "Alt Mode" port. However, the USB-C port is a mixed bag, and the supported functions aren't obvious from the outside. You have to consult the documentation to find out which functions can be used. If "Alternate Mode," "Alt Mode," or "MST" is mentioned, multiple monitors can be connected. However, often no monitor can be connected to the USB-C port, and sometimes only one. On Apple MacBooks, MST only works via Thunderbolt.
Solution for retrofitting an extended desktop
Therefore, a computer with only a single HDMI output cannot be retrofitted with an HDMI splitter to enable dual monitor functionality. One option for such a PC is to use an external USB graphics card, which then provides two HDMI video outputs. This allows for the functionality to be retrofitted for an extended desktop.
We offer such a solution for computers with USB 3.0 or USB-C interfaces. Our USB Dual HDMI Display Adapter CX200 supports Windows and Mac computers and monitor resolutions of 1920x1080 (Full HD) and 3840x2160 (Ultra HD). Instead of a 4K monitor, a monitor with 2560x1440 (WQHD) can also be used. This allows two additional monitors to be connected to a laptop or MacBook in addition to the integrated display. The computer must be reasonably powerful and should have a Core i5 processor or better.
If the computer has a USB-C port with support for Alternate Mode and MST, the CX300 docking station can be used. No drivers are required.
