You should be able to set x12 memory multi if you want, voltages do not matter for that. have you never loaded optimized defaults since installing this CPU? If not, do it now, then save/apply/reboot BACK to the BIOS and set your SATA settings again before loading windows. Then you should be able to set x12 multi, if not the board is limiting the multi not the CPU as that CPU can do many more memory multi's above x10. I'm downloading your BIOS now to have a look, it could just be the board itself limiting that.
If it is, then you will have to run at least 160 Bclk to run the memory at 1600Mhz.
As for ram voltage to 1.64 or 1.66, it will be a little less anyway, so keep in mind 1.64 may be only 1.62-1.63