I did not need to update the BIOS to upgrade from the Original Pentium D to Core2 Duo. However, if you want the BIOS file, you can download from Lenovo’s website support.lenovo.com/us/en/solutions/ht001704-critical-system-bios-update-for-thinkcentre-m55-m55p-m55e-a55-lenovo-3000-j110.