If you want memory higher than 1866mhz you could easily overclock it to the higher speed
The memory controllers on the Phenom II and FX processors are upto 1866mhz. Many boards, especially 990fx boards, like the Crosshair Formula V allow you to overclock beyond this. The Sabertooth 990fx is not one of these, literally allowing you max memory speeds of 1866mhz. You will get 50-100mhz tops more out of it, if your lucky.