ac97_codec is a mixer module, you need it.
check your gcc compiler version "gcc -v" and that compiler version which
has been used to compile your system kernel and other loadable moduls via a
"cat /proc/version ".
Try also a "/sbin/insmod -f i810_audio" and then start the mixer, if sound is
working, fine. If not, try to download the respective nforce package
rpm with PRE-COMPILED drivers for Redhat 8.0.