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System Builder Marathon, March 2012: System Value Compared

Power And Efficiency

Power consumption is one place where slower dual-core processors shine, which gives Paul's effort a chance to top our corresponding chart, where lower numbers are better.

On the other hand, my Core i7-3930K consumes more than two times the idle power of Don's Core i5-2400, even though it only employs two additional cores.

Since efficiency compares work to energy, we first collect performance averages for all tests to determine how much more gets done on the faster systems. Using the slowest configuration as our 100% baseline makes this measurement easy.

Dividing average performance by average power would give us average efficiency, but we weighted our performance charts to account for the 10% maximum amount of time a user might spend waiting for various files to load. The baseline from these calculations starts at 100%, but since nothing is 100% efficient we move the baseline to 0% by subtracting one from the results.

Surprisingly, the $2600 PC actually reaches baseline efficiency when it's overclocked, even though moderate CPU voltage increases were required. The $1300 build shines brightest however, combining an efficient Sandy Bridge quad-core processor with AMD’s moderately-efficient Radeon HD 7970 graphics card.

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.