It looks like a 12 pin PCIe power connector (obviously, double-check for yourself
![Geek :geek: :geek:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
) - which would make sense since they used PC power connectors (as I documented in this thread) for the earlier revisions of the CO monitor too.
It's a bit expensive, but I think this would probably work:
https://www.amazon.com/dp/B0C4B7VMR7
You can probably find better prices on the raw connectors from an electronics supplier or maybe even desolder the female one from a defunct computer/PSU.