UPDATE (11/2012): Latest ASUS BIOS now use CAP format for improved boot times, performance and security. Format rename list is now:
P9X79 DELUXE = P9X79D.CAP
P9X79 PRO = P9X79PRO.CAP
P9X79 = P9X79.CAP
SABERTOOTH X79 = SABERX79.CAP
Rampage IV Extreme = R4E.CAP
Rampage IV Formula = R4F.CAP
Rampage IV GENE = R4G.CAP
P9X79WS = P9X79WS.CAP
UPDATE: ROM rename list is as follows for older ROM BIOS
P9X79 DELUXE= P9X79D.ROM
P9X79 PRO= P9X79PRO.ROM
P9X79= P9X79.ROM
SABERTOOTH X79= SABERX79.ROM
Rampage IV Extreme= R4E.ROM
Rampage IV Formula= R4F.ROM
Rampage IV GENE= R4G.ROM
A video tutorial showing how easy it is to update your BIOS with the new USB BIOS Flashback feature available in ASUS X79 motherboards.