ASUS P7H55-M PRO not outputting in 5.1

[TheArchitect]

I'm connecting my ASUS P7H55-M PRO via optical to my 5.1 home cinema setup but then using the sound effects utility I cannot get it to use any more than the LF and RF speakers, it doest seem to use the sub, rear surrounds or center speaker, do i need to install some codecs or something?

anyone able to help me out?

 

[eyetrip]

It's because it's outputting PCM uncompressed audio, for which optical only has enough bandwidth to feed two channels.

For 5.1 over optical, you would need something which could encode dolby digital or dts, and send that to your receiver, which the onboard for this won't do.

You will need to invest in a soundcard which support dolby digital or dts encoding.