Power management conflict with Realtek drivers. Fix: In Device Manager → Sound Controllers → Apple Audio → Properties → Power Management → Uncheck “Allow the computer to turn off this device.”
However, for security and performance, most users are encouraged to move to Windows 10/11 with Boot Camp 6.x (or newer Apple Silicon workarounds like Parallels/VMware) on supported hardware. On unsupported Macs, version 5.1.5621 may represent the last stable driver set. boot camp support software 5.1.5621
: Drivers for NVIDIA, ATI/AMD, or Intel HD graphics depending on the Mac model. Audio : Cirrus Logic or Realtek audio drivers. Power management conflict with Realtek drivers