The latest BIOS is always recommended. When making new software, ASUS takes into account future CPU's as well as bug fixes. I would try the latest BIOS and work your way back if you run into issues.
Grab it here:
http://www.asus.com/Motherboards/MAXIMUS_IV_GENEZ/HelpDesk_Download/Make sure you read the read-me for the file, in case it needs a special rename to flash properly. Good luck!
Motherboard: ASUS Maximus V Gene v1903. CPU: Intel I7-3770K at 5ghz. RAM: G.SKILL TridentX 16GB at 2400mhz. GPU: ASUS STRIX 980. SSD: Intel 520 in RAID0. OS: Windows 7 Ultimate SP1 x64.