Comment 90 for bug 563156

While Googling around to solve this problem with my Lenovo x100e, I stumbled into some random links about high pitch noise from the computer.

I think the missing sound could relate to this issue. In Windows I hear the high pitch regulator noise and the battery life span is much higher. And I recollect hearing the same sound with some previous version of Ubuntu. Those Ubuntu versions felt like being more power conservative.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/654475
http://forum.tabletpcreview.com/hardware/3516-i-think-i-got-rid-cpu-noise-good-core-duo-please-read.html