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.

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Core i7 920 (2.66 GHz/ 213 W Peak Power) Performance Increase Average Power Increase
3.0 GHz 8.8% 4.6%
3.33 GHz 14.7% 8.5%
3.66 GHz 24.6% 13.3%
3.8 GHz 31.1% 24.7%
4.0 GHz 23.3% 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.

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

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Core i7 920 (2.66 GHz / 213 W Peak Power) Performance Increase Total Power Increase
3.0 GHz 8.8% 3.4%
3.33 GHz 14.7% 5.6%
3.66 GHz 24.6% 11.1%
3.8 GHz 31.1% 20.4%
4.0 GHz 23.3% 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.