I think you mean 1200Mhz for the system bus ? if this is so then it depends on your mother board, if its a single channel version you would need a DDR2/3 capable of running at 1200Mhz for a 1:1 ratio. If you have a mother board that is dual channel ready for RAM all you would need is DDR2/3 600Mhz (600+600=1200) but as always buy the fastest RAM you can afford it will reward you with better performance.