This link is for the CROSSHAIR 4 FORMULA page on ASUS's website. Click it, navigate to downloads section, BIOS and choose the file you want and download it, unzip it then run ASUS BIOS update utility and select update BIOS from file option to install the un-zip'd file
http://uk.asus.com/product.aspx?P_ID=kPGmtxee5RsQVsXG&templete=2
I reset BIOS to default settings before changin BIOS version for safety
You can/should use the other ASUS downloads for chip-set drivers, ethernet drivers etc and you might find newer drivers for some stuff like CREATIVE sound card at the manufacturers website
If your PC is overclocked you could write down the overclock settings before changing BIOS because I think overclock profiles will be deleted
