My first guess would be OC on FSB but anyway.
There is no FSB on LGA1366/1156/1155/etc. CPUs since most North Bridge functions (memory controller, DMI, GPU interface, etc.) are integrated in the CPU.
The only clock the CPU uses is BCLK and because it is used to generate the clocks for nearly everything else including USB, SATA and PCIe, it has very tight tolerances.
The high memory clocks on K-series CPUs are possible due to unlocked memory multipliers. However, as DJ mentioned, there is almost no gain from increasing memory frequency in most cases. In most benchmarks, we're talking 2-3% improvement going from 1066 to 2133 so the steep price for going beyond 1600 makes very little sense.