Efficiency Explored: What's The Perfect Clock Rate For Your Core i5?

OC Settings And Clock Speed Table

The table below lists all clock speeds and settings that we used for this article. Please note that we had to switch off the Turbo Boost feature above 3.2 GHz, as the resulting maximum clock speed would have exceeded the highest reliable speed of roughly 4.2 GHz. Here is an overview of the resulting clock speeds realized when you increase the system clock without modifying the base multiplier (the first column is with a 20x multiplier), but with Turbo Boost enabled (columns with multiplier 21x and 24x):

(*) These settings were unstable without application of additional processor core voltage, which we avoided.

Regardless of possible margins in the thermal envelope of the processor, our Core i5-750 did not operate higher than about 3.7 GHz without a voltage increase. As a result, we found that a 160 MHz base clock was the maximum stable setting we could use with Turbo Boost enabled and without increasing voltage.

Certainly, you can increase the processor voltage in an effort to move default and Turbo Boost clock speeds further up, but this would also result in decreased efficiency in all operating states. Hence, a 160 MHz BCLK with a 3.2 GHz nominal speed and a Turbo Boost speed of 3.36 GHz for three or four cores and 3.8 GHz for one or two cores was the maximum here.

Clock Speed Table