I would think of the ACU as a "handle" to set various parameters on the NIC. Without ACU, you wont be able to set or limit the power of the card to a value from the default. Nor does any of the other features like radio management, world mode and a hell lot more..work without enabling them using the ACU. I think, atleast you will have to write a software interface of your own to enable/disable these features.
An easy way to see the status of the card is to use the LEDs on the card.
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus