HDMI Dummy Plug 4K,Virtual Monitor EDID Emulator, Headless Display Adapter,Headless hdmi Adapter，hdmi Dummy，Supports up to 4k@60Hz,1080@120Hz
You could get a dummy HDMI plug for $3 on Amazon and free up that monitor if you need it. [1]
[1] https://www.amazon.com/BKFK-HDMI-Dummy-Plug-3840x2160/dp/B0C...
