Intel has never been too receptive to the idea of users overclocking their processors; for the longest time, there have been roadblocks in the reference chipsets or the processors that make overclocking harder than it should. For obvious reasons too, since this practice reduces the need for enthusiasts to get a more expensive, higher-end processor. It didn't stop enthusiasts from trying and succeeding, especially since Intel's processors generally have, depending on the architecture, very decent allowance for overclockers to exploit.
The chip giant has slowly revised its attitude, with Intel first releasing Extreme Edition processors with unlocked multipliers for those who wish to push the boundaries. Unfortunately, these Extreme Edition chips are usually premium models with the highest clock speeds, making them impractical for the budget user hoping to squeeze some extra mileage out of their processors. That's all set to change with the introduction of Intel's latest processors - the Core i7-875K and i5-655K. These 'K' series processors appear to be similar to the other Core i5/i7 processors with one major exception - they have no multiplier lock.
A processor clock speed is determined by the processor multiplier and the base clock of the motherboard. A locked multiplier means that the multiplier has an upper limit, though one can still decrease the multiplier. An overclocker then has to increase the motherboard base clock instead during overclocking, which usually means an increase in other related clock frequencies, like the memory clock. This explains why overclockers tend to go for more expensive, 'overclocking' memory modules that have higher frequencies. In short, overclocking currently is about finding a balance between the base clock and the multiplier such that one gets the highest resultant processor frequency.
A processor with unlocked multipliers therefore allows users to simply increase this number without requiring more costly memory or doing more tweaking. It makes overclocking a much more simple affair. This is the main attraction of these K-series Intel processors and we have no doubt that they will be welcomed in enthusiast circles. But as you'll find in the summarized specs below, there's little difference between it and the regular Core i5/i7. In fact, these two new processors have an 'equivalent' version that do not have unlocked multipliers.
||Clock Speed||Turbo Clock||Cores/Threads||L3 Cache||DMI||Max TDP (W)||Retail Price (US$)||Availability|
As a sidenote, the Core i5-655K is based on the 32nm Clarkdale architecture, which has an integrated graphics core on the same CPU package. This graphics core runs at the more common 733MHz clock, not the unique 900MHz that's only found on the Core i5-661.
One other difference between these K-series processors and the regular Core i5/i7 is that Intel's own specifications show that they do not have Intel Virtualization Technology for Directed I/O or Intel Trusted Execution Technology. Since these processors are likely to be used by enthusiasts in desktop systems, the lack of these enterprise related features should have no impact, but if you're one of those who require these technologies, it's something to take note.