Impact of Thread and Frequency Scaling on Performance and Energy Efficiency: An Evaluation of Core i7-8700K Using SPEC CPU2017

This paper describes the results of measurement based studies focusing on performance and energy efficiency of SPEC CPU2017 speed and rate benchmark runs on the Intel's Core i7-S700K processor. We measure execution time and the total energy consumed during individual benchmark runs with 1 thread/copy (IT/IC) and 6 threads/copies (6T/6C) when the processor clock is set to its nominal frequency of 3.7 GHz. Next, we evaluate how changes in the processor clock frequency impact performance, energy efficiency, as well as a composite metric called PE that captures both performance and energy efficiency. We find that IT/IC benchmark runs at the nominal frequency achieve an optimal PE, whereas 6T/6C benchmark runs achieve optimal PE when running at 2.7 GHz.