Standard Xbox BIOSes are tied to the kernel version of the Microsoft dashboard.
Because Complex 4627 modifies the audio driver initialization (to enable debug sound), some v1.6 consoles experience pops or dropouts in Halo 2 or Ninja Gaiden . The fix is to use a "No Audio Patch" variant of the 4627 BIOS. xbox bios complex 4627
: The standard version used by most users for high game compatibility. Standard Xbox BIOSes are tied to the kernel
For everyone else: Use Cerbios v2.4.2 or iND-BiOS 5004. They are safer, better documented, and actively supported. and actively supported.