Fun fact for those who have GPUs with a DisplayPort(well, at least V1.2): You can have up to 4 HDMI displays come from a single DP plug because of Multi Stream Transport(MST). This is a standard that was implemented in GTX 6XX and newer from Nvidia and pretty much any AMD GPU that still runs today and has a Display Port.
To make it work all you typically need is an adapter that costs about $60 USD for 2 HDMI outputs and about $170 for a quad HDMI output. Sounds expensive but graphics cards are expensive right now and trying to have multiple in a PC and gaming with multi monitors is a pain in the butt.