You might have noticed the beeping sound in recent thinkpads (my friends thinkpad T61 had this and my just bought x301 seems to have this too). That high pitch noise appears when your Thinkpad is idle, as in has “nothing” to do. I noticed it disappear when I moved the mouse for example. That is a feature called intel speed step, which slows down the frequency to save power and that then noises around for some reason (as far as I know, I might be wrong, however the steps described here fixed it for me). We don’t need this feature as the kernel can provide something similar:

apt-cache show cpufrequtils
apt-cache show cpufreqd

To disable intel speed step in the BIOS turn on your thinkpad and press the blue thinkvantage button (on the top of the keyboard), then press F1 to get to the BIOS. There go to config – Power – Intel (R) SpeedStep technology and set it to disabled. That should do the trick. If it doesn’t work take a look at config – Power – CPU Power Management.