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Overclocking Core i7: Power Versus Performance

Average And Total Power During PCMark

We looked at the average power requirements during PCMark Vantage, to see the power consumption numbers at a given workload.

Core i7 920 (2.66 GHz/ 213 W Peak Power)Performance IncreaseAverage Power Increase
3.0 GHz8.8%4.6%
3.33 GHz14.7%8.5%
3.66 GHz24.6%13.3%
3.8 GHz31.1%24.7%
4.0 GHz23.3%50.4%

*Core i7 Overspeed Protection led to throttling

While the average power consumption increases by a maximum of 24.7% at 3.8 GHz, going one step farther to 4.0 GHz results in a jump to 50%. Compared to the 36% increase in idle power paired with a performance increase of 23.3%, the 4.0 GHz setting does not make sense from a practical standpoint.

Finally, we also looked at the total power used to complete a PCMark Vantage run:

Core i7 920 (2.66 GHz / 213 W Peak Power)Performance IncreaseTotal Power Increase
3.0 GHz8.8%3.4%
3.33 GHz14.7%5.6%
3.66 GHz24.6%11.1%
3.8 GHz31.1%20.4%
4.0 GHz23.3%50%

Keep in mind that the total power used does not increase that much, as the faster system typically terminates its computations more quickly, allowing the system to switch into a power efficient mode.