It depends on the BIOS. Does the BIOS allow you to set different speeds for your RAM?
I just checked newegg, there is an z68BC which says
Memory Standard: DDR3 1600/1333/1066
while z68DB says
Memory Standard: DDR3 1333/1066
so will it work ?
Im in India there is very little stock over here. Would have preferred an Asus but forced to go with intel mobo.