More to the point, you chose DDR3 RAM which won't fit in these DDR2 motherboards. I don't think I've seen any socket 775 mobo's which support DDR3. If you're going with C2D, just pick out a nice set of DDR2-800 and run with that- it's good to FSB1600. If you want to OC higher than that, you'll need to step up to DDR2-1066 (aka pc2-8500). The faster RAM will downclock to the FSB. So if you're running FSB1333 (stock for current C2D lineup) the RAM will downclock to 667, even though it's rated for 800 or 1066.