Default reference clock is 100MHz, the multiplier for stock clocks is 34 (34*100=3.4GHz). If your RAM speed is set to 1866Hz, your base clock (100MHz) is being multiplied by 18.66.
So if you wanted to OC the RAM speed (keeping the 1866MHz divider) and keep your cpu speed at stock clock then you can adjust your reference clock and cpu modifier so multiplied together they will equal 3.4GHz and your ram speed would be your new reference clock mulitplied by 18.66.
For example: 106MHz (ref clock) * 32 (cpu multiplier) = 3.392Ghz CPU speed (approximatley stock) and 106MHz * 18.66 = 1978MHz RAM frequency (overclocked RAM)
So in this instance a mulitplier less than 32 will be underclocking the CPU
You will also need to drop the northbridge multiplier else you're overclocking it when you up the reference clock
Edited by MustardCutter - 12/20/12 at 9:13am