What Is An HDMI Port ‘Dummy Plug’?

We may receive a commission on purchases made from links.

The High-Definition Multimedia Interface (HDMI) standard has been around since 2002 and is now the most popular way to transmit a video signal from a device to a screen. But what if you don’t need to transfer video to a monitor, and still want to use your device? That’s where an HDMI dummy plug comes into play, enabling what is known as headless operation. This might sound painful, but in the HDMI world, it simply means you can run your system without a monitor attached. 

These plugs trick the host computer into thinking that a monitor is attached when one isn’t. One great example of the usefulness of an HDMI dummy plug is when you have to leave a computer running for long periods, perhaps for home automation, and you don’t need to access the monitor. Having a monitor and cables takes up a lot of space, especially if you are using a small form-factor PC for various automation tasks.

The power consumption of a monitor may also be a concern for many who might be leaving a PC running all hours of the day. And perhaps most important for many is using an HDMI dummy plug for game streaming: if a monitor isn’t attached, your GPU might not be able to output at full resolution, since it’s looking for a monitor to set the desired output size.

HDMI dummy plugs are popular in the world of crypto mining. You’ll often see banks of graphics cards used for mining with HDMI dummy plugs. This allows the machines to run and mine without each GPU needing its own monitor. This drastically reduces the space needed while also lowering power consumption, since you don’t need dozens of monitors running simultaneously.

Many gamers also rely on an HDMI dummy plug to improve performance when streaming game content. When you emulate an attached display, the HDMI dummy plug lets you use more power and higher resolutions than your graphics card supports, which is really helpful when streaming PC content to a handheld. Adjusting power modes and various higher resolutions are often disabled when a system doesn’t register that a screen is attached.

Another use for an HDMI dummy plug is when you are running a backup machine at home. I use a small-form-factor computer very similar to the GEEKOM A8 Mini PC, which I installed several large SSDs into. This serves as the family backup for photos and videos and also streams media content to every TV and device in the home via Jellyfin. With a dummy plug, I can remotely access the computer on my phone through several applications to manage my content while keeping the PC tucked nicely away and out of sight.