hdmi cable to LG tv no audio
i have my pc connected to a LG flatron 22" tv by hdmi cable the picture is fine but the audio does not play through the tv, a jack cable from the pc to the tv does not work either, if i use the jack plug into separate speakers it will play the audio through the speakers. i have checked in play back devices that the tv is default device, checked audio and graphics card drivers they are all up to date.
pc specs are:
cpu: amd phenom ii x4 BE 3.4ghz
mobo: asus m4n75td
graphics card: 2 x nvidia gefore 8800 gs in sli
stuck on what to try next any help would be appreciated