I used to use onboard sound and it did a very good job with a 5.1 system with those multicolored 1/8" jacks.
Then I moved to a receiver with a home theatre 7.1 setup and discovered that the optical out on my onboard audio only does stereo as confirmed by the board manufacturer.
Regrettably, I am now using a Soundblaster drop-in until I upgrade the whole system and find a board that supports 7.1 Dolby on optical.
"Just take a look around you, what do you see? Pain, suffering, and misery." -Black Sabbath, Killing Yourself to Live.
“Man was born free, and he is everywhere in chains” -Jean-Jacques Rousseau