Onboard sound is sound that is built onto the motherboard. A sound card is one that was installed seperately. To tell when you look at the back of your machine does you speaker input go in toward the top where your keyboard and mouse plug in or does it go in down blelow? If it gets plugged in lower toward the bottom of the case that means that a sound card was previously installed. So the way to find the make and manufactor the added in sound card is to open the case and look. If not then do as i suggested above to find the make and model of the onboard sound card.
I do not accept support questions via EMail, PM, IM or my G+ page!
Phone: LG Optimus G Pro
Running: Stock JB from LG with Nova Launcher