Are you sure you have the connectors plugged in in the right order/ports? There should be a green, blue and pink port at the rear I/O where the green is the front, and the blue will be retasked as a rear output while the pink will be the standard mic input port.
*are you sure that that is the model number for your motherboard?
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CPU-Z, take screenshots of all the tabs and then link them back here after uploading on an image hosting site. Please include your OS as well.
If you're working with an onboard Realtek audio solution then download the latest drivers from
here and see if the issue is resolved.