The Tech Report: "When we first reviewed the Core i7 processor, we had two chips on hand: the high-end Core i7-965 Extreme and the more affordable Core i7-920. Sandwiched in between them in Intel's product lineup is the Core i7-940. Since we didn't have one of those to test, we employed a trick we sometimes use and turned down the clock speed on our Core i7-965 Extreme from its native 3.2GHz to the 940's 2.66GHz frequency. Given the breadth of CPU model ranges these days, we find ourselves using this trick fairly often. In fact, in this case, Intel even recommended that reviewers use this method to test Core i7-940 performance and provided the media with instructions for setting the proper clock speeds.
But such an approach always comes with caveats. Although we're usually confident that the performance results of a "simulated" product model, using the same silicon and the same clock speed, will be true to the original, we're less than confident that the power consumption results will match the actual chip. In fact, power consumption can vary from one individual chip to the next, along with the voltage, which is set at the factory. Beyond that, there is the slight possibility that our simulated product might somehow not match the original in terms of its configuration-and thus performance."