We are often asked which HDMI splitter can be used to operate 2 monitors on one PC at the same time. In principle, this works with any of our HDMI splitters or HDMI matrix switches . Both screens show the same image. In the PC world, this is called "mirroring" or " mirror mode ". What will never work, however, is using an " extended desktop ". In such a dual-monitor work environment, each monitor shows a different part of the desktop menu. The work area is doubled - a great thing. But unfortunately this cannot be achieved with just one HDMI output on the computer. A splitter is no help here either. The 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 2 screens that show a different image! This is because an HDMI connection does not support the necessary "multi-stream transport" (MST). Only DisplayPort and USB-C "Alternate Mode" or "Thunderbolt" connections on the computer can do this. An extended desktop can therefore only be displayed via HDMI if the graphics card already has 2 HDMI outputs. Or if the computer has a DisplayPort connection that supports MST. It also works if the computer has a USB-C "Alt mode" connection. The USB-C connection is a mixed bag, however, and the supported functions are not visible from the outside. You have to look in the documentation to see which functions can be used. If "Alternate Mode", "Alt Mode" or "MST" is mentioned, several monitors can be connected. However, often no monitor can be operated on the USB-C port, and sometimes only one. On Apple MacBooks, MST only works via Thunderbolt.
solution for retrofitting an extended desktop
The dual monitor function cannot be retrofitted using an HDMI splitter on a computer with only one HDMI output. One option for such a PC is to use an external USB graphics card, which then offers 2 HDMI video outputs.
We will be offering such a solution for computers with USB 3.0 or USB-C interfaces from summer 2024. Our USB dual HDMI display adapter CX200 supports Windows and Mac computers as well as monitor resolutions of 1920x1080 (Full HD) and 3840x 2160 (Ultra HD). This means that 2 additional monitors can be connected to a laptop or MacBook in addition to the integrated display. The computer must not be too low-performance 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 could be used. No drivers are required.
