The Intel Core architecture is one that has not always been a performance leader. The original Core CPUs were decent, but not that great. Starting with the Conroe based Core 2, things changed. We saw Intel push the limits on performance at both stock speed and also for overclockers. With the launch of the Nehalem and Lynnfield CPUs we saw Intel greatly improve stock performance, but overclocking, while still pretty good, was not the same as it had been, especially for the top of the line CPUs.
To help offset this Intel has released a new "K" line of CPUs that are multiplier unlocked. This means that you have control over the multipliers for the CPU ratio and memory ratio, giving more options for a better overclocking experience.
While we already have the unlocked Core i7-980X for socket 1366, today marks the release of the i7-875K for socket 1156 and the i5-655K also for socket 1156, but which includes the Intel GMA HD video processor. We are taking a look at the Core i7-875K today to see if it can indeed give us more.