No, unfortunately it isn't shouted about too much and I only discovered this after I had spent ages trying to get my 1600 Mhz Corsair RAM to run at stated speeds. Eventually I had to bring it down to 1333 Mhz where it ran quite happily.
However, same memory, same motherboard (GA-790XTA-UD4), new Phenom ii X6, new BIOS and hey presto, my RAM is now running at 1600 Mhz. But if I use the old X4 it will still only run at 1333 Mhz.
(Update) Sorry should have mentioned that this is with 2 x Corsair Dominator CMD4GX3M2B1600C8 (8 Gig total)