How the Methodology Works

As shown earlier, EEP 2.0 methodology is built on six SYSmark* 2007 Preview runs per day. Standard benchmarking practice runs each benchmark three times and uses the median of the three runs. For illustrative purposes, however, we will use a single run. The key metrics for EEP 2.0 are performance, as represented by the SYSmark* 2007 score, and the yearly system energy cost.

In order to calculate the energy cost, the PC must be monitored for actual energy consumption during the run. While this can be done with a simple, inexpensive plug-in wattmeter, a more sophisticated meter with data logging is preferable since it samples power consumption continuously and the amount of time spent at that power level can be calculated or imputed from the recorded data.

Intel’s measurements presented here used a sampling rate of 2Hz, or twice per second, with a wattmeter capable of automatic data logging. The testing protocol measure power during each of the SYSmark* 2007 Preview’s four component test. At the end of each test, the meter is stopped, since SYSmark* 2007 Preview reboots the system between sub-tests.

The information to be captured includes: * The time it takes each SYSmark* application segment to run (may be captured by stopwatch or the wattmeter). * The average power consumed during this time (captured by the wattmeter automatically or something that will have to be calculated manually from the captured sample). * To ensure stability of measurements, testers should perform five runs to capture Windows* Vista’s dynamic tuning capabilities in the test results, and then take the median of those five scores.

Next, measure the idle and Standby system power-draw levels.

For idle, allow the system sit for at least seven minutes with no active applications running on it, take samples over a three-minute period, and then calculate average idle power from those samples.

To measure Standby system power-draw, go to the Windows* Start Menu, and select Shut Down. Then select Standby and the system will go to Standby mode. Take samples over a three minute period, and then calculate average standby power from those samples. We recommend using average power value for idle and sleep states rather than median values, because the average captures the small fluctuations that occur in power-draw when in these two states.

This methodology can be applied to platform evaluation irrespective of the platform’s energy savings settings. Note however that for best energy efficiency, users should enable features like Enhanced Intel® SpeedStep™ Technology, whose benefits include achieving optimal idle power energy-efficiency. This technology exists to enable better energy efficiency, and should be used to minimize energy use when the computer is not being used. With that in mind, tested platforms presented here had Enhanced Intel® SpeedStep™ Technology enabled.