I had four unused HDMI cables. One day, I needed to send a signal from my PC to my tv. I usually use Plex for convenience and the "resume where I left off" feature, but that day a certain update was acting up, so I decided to use a cable instead. Easy. The next day, I wanted to send a signal from my laptop to the tv downstairs (I still hadn't fixed the Plex issue) and pulled out the second cable because I needed a different length than the first one... but it turned out to be incompatible, so I ended up using the third one.