A little over a year ago, Intel very discreetly launched of the Pentium E6500K processor in mainland China. The 'K' in the name meant that the chip had an unlocked clock speed multiplier, à la AMD's 'Black series' CPUs.
The market was surprised, as the chipmaker had previously taken great lengths to keep the overclockers at bay, and this was probably the plan born of test-tube mentality.
Surprise turned to luke-warm reception as the processor chosen was a mid-to-low range processor. Needless to say, it didn't rally enthusiasts into mobbing stores to get their hands on one of the precious K series.
Fast-forward to May 2010, and Intel launched more K series CPUs, only these were Core i5 and i7 (model numbers 655K and 875K respectively). Many speculated that the integrated memory controller would be a great obstacle to achieving ultimate overclocking performance, but it seems it hasn't stopped quite a few people from trying.
At the beginning of the month, a very competent and well-known overclocker, duck, managed to squeeze 7307.84MHz out of his Core i5 655K Clarkdale, as validated on Canard PC's CPU-z site. Although he doesn't describe that cooling has been used isn, the feat required setting a 33x multiplier in BIOS and a bus speed of 221.45MHz. The two gigabytes of DDR3 memory were running at a conservative DDR3 1066MHz setting, keeping things in check.
That's 7.3GHz... Not too shabby for a £160 processor, is it?
Ironically, the fastest validated CPUs on record are rather dated Celerons (347, 356) and Pentium 4 (631) of all things, with recorded clock speed of high than 8.1GHz. Considering these are 65nm processors, maybe there was some ground to that age-old NetBurst ambition of reaching 10GHz...
The slowest of the slowest CPU honour goes to a Pentium Overdrive, which has been clocked down to a barely-alive 7.07MHz. Something that will definitely not play Crysis in any form or shape.