Have you seen this video about the combinations possible with supermicro backplanes?

https://www.servethehome.com/supermicro-cse-ptjbod-cb1-jbod-power-board-diy-jbod-chassis-made-easy/

A fridge won’t work. A chiller, on the other hand… those you can get rated for a couple thousand BTU/hour without needing a second mortgage. Still not cheap though, and it would be on top of the cost for a water cooling loop for each machine.

I’m probably close to 4-5w/TB but I’ve also got 640GB of RAM, dual Skylake Xeons and a Tesla P40, it’s doing far more than just plex.