The CMI8738 is legacy hardware (circa 1998–2005). No official signed 64-bit driver exists from C-Media for any modern Windows OS beyond Windows XP/Vista (32-bit).
Find the CMI8738 device (it may appear as "Audio Controller" with a yellow exclamation mark). Right-click it and choose Update driver Manual Search "Browse my computer for drivers" followed by Cmi8738 Driver Windows 11 64 Bit
: Third-party databases like Treexy and DriverMax list "Windows 11" compatibility for certain CMI8738 variants, though these often use the same Windows 10 base driver. Installation Steps for Windows 11 The CMI8738 is legacy hardware (circa 1998–2005)