Does the CPU always need unswitched/undimmed 120-277VAC?

YES! 

The CPU consists of both the Driver and the Main Processor. The Driver needs to be provided CONSTANT, unswitched, undimmed power in order to power the Main Processor, which controls everything about the VENTRIX system (Wifi connectivity, fixture control, etc).

If a customer needs to use a dimmer, additional wires will need to be run between the dimmer and the VENTRIX CPU, directly into the dimmer ports on the VENTRIX Main Processor. This is the case even for TRIAC/ ELV dimming.