Intel EIST SpeedStep

Similar to our first test in the AMD Cool 'n' Quiet article, we began by allowing the ThinkPad R52 to idle in GNOME v2.10 at 1400 x 1050 with the screensaver disabled. The idling process had lasted for about 30 minutes, and after that time had finished, the power consumption was recorded from the Seasonic PowerAngel and the CPU temperature was gathered from /proc/acpi/ibm/thermal. The same process was repeated again, but rather than being powered by the outlet, it utilized the battery, and after 30 minutes had expired, the present battery discharge rate was recorded via /proc/acpi/battery/BAT0/state. This entire process was done for each of the five Intel SpeedStep performance levels with the Pentium M 750 (1.86GHz, 1.60GHz, 1.33GHz, 1.06GHz, and 800MHz). In order to over-ride the automatic frequency and voltage levels, we used cpufreq-set to manually specify the operating frequency.