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Energy Consumption of Apple Macintosh Computers

Lorch, Jacob R.
Smith, Alan Jay
Technical Report Identifier: CSD-97-961
June 17, 1997

Abstract: The utility of a portable computer is critically dependent on the period it can be used while running off the battery. In this paper, we present a study of power consumption in Apple Macintosh computers. We measure the existing power consumption for each system component using built-in measuring tools. Since total power consumption is a function of user workload, we use eight user workload traces to determine power use as observed in practice. Apple currently implements some power-saving features, and the effectiveness of those features is estimated; we find typical power savings of 41-66%. After the use of basic power-saving techniques, we find that the major power users are the backlight (25-26%), the CPU (9-25%), the display (4-17%), the video circuitry (6-10%), and the hard drive (4-9%). We then evaluate possible changes in system hardware and software with regard to the power savings they might offer.