Intel have been churning out i7 920s for so long that their fabrication section have absolutely got the design and production process nailed. The original 920 C wasn't exactly bad, but it definitely suffered from a little too much heat and the overclocking abilities varied wildly depending upon the batch your processor came out of. Some barely cracked 3GHz while others found 4GHz to be a breeze. Intel nearly fixed this with the release of the D0 stepping variant of the 920. This had much more consistent performance although some still did better than others. The main reason for the more reliable overclocking ability was the reduction in the heat output which was such a large part of the 920 C0/1 limitations.



Link: Overclock3D