What diagnostic software? as the only thing i can find for AC97 modem is about Linux drivers:
The goal of the AC '97 Modem Driver project is to develop an open source Linux device driver to support the modem functionality of the AC '97 Codec,
I have no idea waht that means but somone might.
Does the sound work? maybe the sound drivers need to be installed,Or maybe you need to insert a device/modem into the AMR slot on the mobo,apart from that i have no idea.