Which makes me wonder - are we going to also need a separate 5v power supply adaptor? Or is there such an adaptor that can convert one of the connectors from a PSU to that fitting?
Yes, I think you will need a 5v connector as well. I believe all ATX power supplies have them. When KNC announced the case, they mentioned the 5v connector as well as the 12v.
https://www.kncminer.com/news/news-28