ThinkPad x61 is one of the best laptops ever produced, period. In fact they are one of the last laptops using the golden 4:3 screen ratio. However I desire 0dB laptops and nearly bought a fanless Zenbook UX305A. I bought a UX31E before and even being one of the quitest laptops around, they are too loud for me.
Using an under-volted external fan, the near-0dB silence was achieved.
1) Install the program to control the fan speed called "TPFanControl"
https://sourceforge.net/projects/tp4xfancontrol/
2) Buy a ThermalTake Pure8 80mm fan ($8) and power it using 9v which. Cut a small piece of cardboard to create a 'tunnel' towards x61's vents and direct the airflow INTO it.
At 9v, the external fan is so quiet it is absolutely inaudible at 30cm distance from my ears. In fact my wife's Zenbook UX21e's fan at 3 meters away was piercing my ears in this quiet nigt! As I type this the ThinkPad's temperature is sitting in a cool 56° celcius.
The inward flow of air is fine, when absolutely needed, X61's internal fan is strong enough to counteract the flow. I've never needed this except when running CPU load tests :). The added bonus is cooling airflow on top of the keyboard. No more sweaty fingers in summer.
I'm sure this would work on other ThinkPad models such as x40 or x41 as well as they have similar cooling hardware.
Have a quiet night !
Discussions on ThinkPad forum here:
http://www.thinkpads.com/forum/viewtopic.php?f=30&t=120837
