Yep, it's called a memory multiplier, depending on the Bclk you have set you can adjust the memory speed with the multiplier.
Bclk: 140 X 10 (multiplier) = 1400 Mhz
Bclk: 140 X 8 = 1120 Mhz
Bclk: 140 X 6 = 840 Mhz
and so on
O/C'ed the cpu and the ram to 3.498Ghz and 1660mhz and it stable thanks