to disable onboard sound it in the bios under onboard devices. (hd audio). set it to off. also if this is a new build you have to install the motherboard chipset drivers first for the pci bus to work right. also on some pci slots you may have to set the speed to 1x or turn the slot on in the bios.
Can you please walk me through how to do these thing. I have been trying to get this to work for like 10 hours. This was built by Cyberpower PC so I don't know if they installed that stuff.