Simple, Assuming you are running windows-7/64
Download bios here~http://www.asus.com/Motherboards/M5A78LM_LX_V2/#support_Download_30
Version 1302 is the latest
Extract the download package
Copy & paste the CAP. file only, to a usb drive. (that is the complete bios)
Go into bios & run EZ-flash
select the CAP. file
Hit yes @ the "are you sure you want to flash" prompt.
2 minutes, its done, Restart computer & set up your new bois settings.