AC'97 settings in Linux....??????

Hello Dears....
I am using Fedora Linux, and I have AC'97 built in sound card on my Intel 845 Chipset...
I have no sound in system.. I have to use start/system setting/soundcard detection every time when I boot linux...
After detection there is no sound again...why???????????/

How can I solv this problem permanently........ I have been use
insmod ac97
insmod i810_audio (default setting after booting)
modprobe ac97/i810_audio

These are notworking...................... Any suggesions