For the "FSB" at 2000MHz, that's actually the HyperTransport Bus that's in lieu of the FSB. It's linked to the memory speed (200MHz, PC3200, DDR400 speeds), and then multiplied. For Socket 754 chips, it's a 4x multiplier; Socket 939 and AM2 use a 5x. This results in an 800MHz or 1000MHz HTT, respectively. HTT also operates at DDR terms, meaning that the net effect is 1600MHz or 2000MHz.