You can find the latest official builds through community-trusted sources like xbins.org .
Hold on boot to force UDMA2 mode, which is vital for troubleshooting hard drive issues (Error 9 or 13). Customization cerbios xbox bios v3.0.0 beta
Hold on boot to force UDMA2 mode, which is vital for troubleshooting hard drive issues (Error 9 or 13). Customization