Look for EOCP, and enable it, then select 1866 - also might check with CPU-Z in the memory tab and check freq, it should be half the data rate you are running - i.e. if it shows 800 then you are at 1600
Look for EOCP, and enable it, then select 1866 - also might check with CPU-Z in the memory tab and check freq, it should be half the data rate you are running - i.e. if it shows 800 then you are at 1600