When you look at the SPD tab of CPU-Z you should see multiple possible settings for your RAM. They will be labeled JEDEC #1, JEDEC #2, etc. These are all of the possible settings your RAM has been programmed to run at. Your computer could pick up one of those settings and use it, or you can configure your own.
Go into BIOS and choose Load Optimize Defaults. Then save your settings and exit, your computer will reboot. If you've made any non-memory related BIOS changes, go back into BIOS and reset those values. This time when you save and reboot, log into windows and open CPU-Z. On the memory tab, the DRAM Frequency should show ~666 MHz. If it does not, you will have to set more values by hand which is not a big deal, what is the DRAM Frequency listed as?