Here is an interesting article about PowerTop: http://www.phoronix.com/scan.php?page=article&item=ubuntu_1404_powert... The conclusion page 4: “while running these various benchmarks and its many periods of idling, there's still a clear win for PowerTOP” “the average power consumption dropped from 25.6 Watts to 22.9 Watts […] The peak power […] from 34.6 Watts to 32.0 Watts. […] when the system was idling went from 12 Watts to 10 Watts. These power-savings happened without regressing the Linux system performance at all.” Thank you, Alexandra.