Go to the "Advanced" tab and the RAM speed adjustments are in the "Jumperfree Configuration" section. Set "Ai Overclock Tuner" to "Manual" then you'll see the "Dram Frequency" section where you can set the memory speed. The "400mhz" setting = 1:1, the "333mhz" setting = 5:4, the "266mhz" setting = 3:2. Those are your choices of dividers on this board.