There are, however, also some downsides to this machine. Sometimes it gets quite noisy while doing low CPU-intensity stuff, and the battery doesn’t last as nearly long enough.

A good way of getting around these problems, is simply to turn off one of the CPU’s cores when you don’t need it. This in turn makes it possible to turn down the CPU fan a little giving us a quieter and more energy-efficient system.

Controlling the CPU’s

Turning off one of the cpu’s goes as follows. Become root and type the following in a terminal

$ echo 0 > /sys/devices/system/cpu/cpu1/online

In case you want to turn it back on, it’s just as easy

$ echo 1 > /sys/devices/system/cpu/cpu1/online

Controlling the CPU fan

Update: To make the following work, you must first run

$ modprobe -r thinkpad_acpi

$ modprobe thinkpad-acpi experimental=1 fan_control=1

Now, we want to turn down the CPU fan. Generally, one should be careful when doing this, since it could result in burning of the CPU. I never had any problems, but proceed at your own risk!
There are 7 fan levels, where 7 is the maximum. A good balance between cooling and noise is achieved using level 2. To do this, use the following command

$ echo level 2 > /proc/acpi/ibm/fan

Turning it back to automatic fan control goes as follows

$ echo level auto > /proc/acpi/ibm/fan