I have had three MSI motherboards with this same issue... If I install a Ryzen 3 2200G with integrated graphics or with a GTX 1060 video card all works as it is supposed to. However, if I swap out a Ryzen 5 2600 the Realtek onboard audio is no longer detected. I have had this with an MSI B450M Bazooka and (2) MSI B450M Bazooka MAX Wifi boards. I have never heard of a faulty CPU causing sound issues, but could this be the case? It is a used CPU, but all the pins appear to be straight and I've build hundreds of PCs over the years. Has anyone got a suggestion. (MSI support was zero help, as anticipated.)