Earlier,we have seen a screenshot of haswell being overclocked to 7 GHZ but at present someone have oc'ed an haswell core i7-4770k to 8 ghz Theoretically, the CPU shouldn't be able to go above 8 GHz due to restrictions with the multiplier and base clock, even on the "*K" version. The video shows the CPU with only two cores enabled and HyperThreading disabled. The voltage of the CPU reaches 2.259 V as the CPU's clock speed is gradually increased. Sadly, it shows nothing about temperatures, and for all we know, this video might well be a crafted fake, nothing but numerous edited screenshots in a slideshow, filmed to trick us into thinking otherwise. We cannot be certain, but the video below is still impressive.
SOURCE:http://www.tomshardware.com/news/Intel-Haswell-Overclock-i7-4770K,22454.html