I too am trying to get my P4S533-MX sound working but my MB is listed as AD1980. If you find an answer to your problem I would certainly be interested in hearing it. I did manage finally to get the NIC configured but that is different on my MB too. It is a SiS 900. I might add that until I turned off PNP OS in the BIOS my soundcard was disabled now it is enabled and my NIC works but still no sound. So the PNP disable might be your answer as you are using Red Hat 9, I am using Red hat 8. Anyway....could sure use some help.
pepper.joe@msa.hinet.net