Using a big, under-volted external fan, the near-0dB silence was achieved!
http://fixedmyself.blogspot.com.au/2016 ... d-x61.html
https://1.bp.blogspot.com/-n80WWFt7GYo/ ... %2Bx61.jpg
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 instead of the standard 12v. 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 night! 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
I'm sure this would work on other ThinkPad models such as x40 or x41 as well as they have similar cooling hardware. I guess one consideration is the long-term accumulation of dust. Might need to check it in a year or so.
Have a quiet night !



