Just put together my first home build. Everything went well. But, my memory is listed as 1600MHz in BIOS but it is DDR3-2133 memory. If I just change it in BIOS, whats the worst that could happen? The voltage was already correct 1.65V, I dont remember the timing, but I'd check that and change if necessary too.
Asus Rampage IV Formula X79
SB spec is 1333, So ddr3 . 1333 would initially come up at the default spec of 1333.
Same with IB except spec is 1600 so any Ram >1600 would initally load at 1600.
When using ram > than the spec, in both IV and SB. the simple solution is to go into Bios and select XMP, Profile 1 which will then load the settings that are stored in the Ram Module (manufs specs).
NOTE: With SB if you run ram that is over the Spec (1333 for SB) you void the warranty (suspect the same will be true with IB). With SB you can buy a OC warrantee (ie $25 for i5-2500k) that gives you a FREE pass if you "blow" your CPU`
Whats covered bassicly (with SB) is:
1) exceeding max Vcore of 1.5 V (Not sure, But does run hotter at voltages used for SB)
2) Exceeding max Memory Voltage of 1.575 V (probably the same for IB)
3) Running your Ram > 1333 (1600 for IB)
Added: side Commnet - DON'T forget, Run Memtest 86 from a Bootable CD BEFOE: Updating Bios, Loading your Operating system, and If SSD, before updating firmware of SSD!!!!