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

3 GHz? 4 GHz? Not a problem! Pretty much all Core i5 and Core i7 models are capable of running at overclocked speeds, delivering stellar performance. You only need a suitable platform to sustain your overclocking ambitions. However, even such an efficient product as the Core i5/i7 will no longer be energy-friendly if clock speeds are tweaked to the extreme. We looked at the Core i5-750 and overclocked it (with Turbo Boost enabled, per your requests) to find the clock speed that delivers the most optimized performance per watt.

How Much Overclocking is Good?

Efficiency and power consumption have become an integral part of evaluation the latest CPUs, in addition to the performance, value-added features, and cost already commonly discussed. Preserving natural resources worldwide is a hot topic for debate, of course, and we’d never encourage anyone to burn energy unnecessarily. But when we’re talking about PC hardware, one has to moderate being eco-friendly with getting stuff done. This is not about trying to save the world. This is about maximizing system value with a focus on sense and reason.

Some years ago, when overclocking wasn’t as popular and widespread as it is today, enthusiasts mainly wanted to maximize performance. This was a logical step. Faster systems—and processors in particular—were highly desired, whereas even today’s entry-level PCs have sufficient horsepower for pretty much all mainstream PC applications (a handful of games excepted). Expense wasn’t measured at the outlet like it is today. Rather, heat dissipation was the major issue once the platform was capable of decent overclocking.

In the first half of this decade, AMD and Intel both cranked up the heat with their processors, moving thermal limits from roughly 30W in the Pentium III days to a maximum of more than 130W. Certain chips, such as the fastest Pentium 4 CPUs, were even forced to throttle clock speeds when they hit their thermal limits. This is when we first started to wonder whether an additional 20% clock speed at the price of almost doubled power consumption made sense.

Hunting Down the Sweet Spot

We’ve already looked for the best ratio between overclocking, performance, and power consumption in an effort to find the most efficient operating parameters for Core 2 Duo, Core i7, and Phenom II X4. For more on those stories, check out:

Overclocking Core 2 Duo: Power Vs. Performance

Overclocking Core i7: Power Vs. Performance

Optimizing Your Phenom II Overclock For Efficiency

Now it’s time to do the same with Intel’s Lynnfield-based entry-level model, the Core i5-750, which we consider one of the best and most reasonable choices for mainstream users with performance ambitions.