There is a cmi9738 on the motherboard, but it is controlled by the sis chip, and the BIOS defaults the on-board sound card to off, so you must turn on the sis-7012 ac97 audio item for the cmi9738 to work.
Press del to enter sis onchip pci device in integrated peripherals in bios, press press enter, enter setup sis-7012 ac97 audio, change it from disabled to enabled, save and exit, reboot, and the prompted to find the new hardware, the problem is solved.