Hi, Most probably boards would need a BIOS update.
Here's the CPU Support List from ASUS for M5A-78L-M LX:http://support.asus.com/cpusupport/list.aspx?SLanguage=en&p=1&m=M5A78L-M%20LX&hashedid=5YkHeMJXc3aijWxY
8350 is not listed. It might work though.
However for updating the BIOS on that board you would need an old supported CPU.