4K HDMI Dummy Plug, Headless Ghost Display Emulator,[3840x2160@60Hz New Generation],High Resolution Virtual Monitor Display Adapter Headless for Mining, Compatible with Windows Mac OSX-6 Packs - Newegg.com
CINEGEARS Ghost-Eye 700M Plus Hybrid HDMI/SDI Transmitter 6-7042
Amazon.com: DTech 4K HDMI Dummy Plug Display Emulator Headless Ghost Adapter Compatible with Windows Mac OSX Linux Support 4kx2k 2160P 1080p for Computer Desktop (fit-Headless, 5 Pack) : Electronics