onboard sound does not work

[moak at bredband.net]

Hello.
I am a newbie to both unix and FreeBSD. I am trying to configure my onboard 
sond without success.
 My motherboard: ASUS P4S800-MX 
Audio spec: ADI AD1888 6channel audio codec.
pciconf -lv says:
pcm0 at pci0:2:7:  class=0x040100 card=0x810d1043 chip=0x70121039 rev=0xa0 
hdr=0x00
    vendor   = 'Silicon Integrated Systems (SiS)'
    device   = 'SiS7012 PCI Audio Accelerator'
    class    = multimedia
    subclass = audio
dmesg:
pcm0: <SiS 7012> port 0xa000-0xa07f,0xa400-0xa4ff irq 18 at device 2.7 on pci0
pcm0: <Unknown AC97 Codec (id = 0x41445368)>
I have put snd_driver_load="YES" in /boot/loader.conf. 
I have device pcm in my kernel. 
Is there something more you need to know??
I have read man pcm, the handbook and complete freebsd but I can t figure it 
out. I still think that everything is a bit confusing because i am not very 
good at computers and i am sure that I miss something fundamental.
Hope that somebody can direct me to what i am missing.
Many thanks Gaf