In our quest for simplicity and low cost, we decided that eliminating the pump was a key objective. Enter the Thermosyphon. What attracted us to thermosyphons is the utter simplicity of it all – a closed system with no pump requiring no maintenance. In addition, the working fluid can be non-conductive and non-toxic, desirable characteristics for any liquid cooling electronics. [via] Link.
Thermosyphons – Better Approach to CPU Cooling?