Fascinating. Your comment got me to go googling for research on heat dissipation in 3D chips. A few links: http://www.electronics-cooling.com/2013/03/measured-

Fascinating. Your comment got me to go googling for research on heat dissipation in 3D chips. A few links: http://www.electronics-cooling.com/2013/03/measured-thermal-resistance-of-microbumps-in-3d-chip-stacks http://www.electronics-cooling.com/2013/03/measured-thermal-... which evaluates an approach of positioning wiring and soldering in each layer so they transmit heat vertically up to the heat sink. http://www.nature.com/news/computer-engineering-feeling-the-heat-1.11993 http://www.nature.com/news/computer-engineering-feeling-the-..., which mentions among other things microfluidics where fluid flows through microscopic channels etched into the silicon. Another great quote: "In a computer, as much as 96% of the machine's volume is used to transport heat, 1% is used for communication (transporting information) and just one-millionth of one per cent is used for transistors and other logic devices. By contrast, the brain uses only 10% of its volume for energy supply and thermal transport, 70% for communication and 20% for computation." http://www.sematech.org/meetings/archives/3d/8334/pres/Fukushima.pdf http://www.sematech.org/meetings/archives/3d/8334/pres/Fukus... has some neat pictures of simulated heat maps. http://www.me.gatech.edu/featured_3Dchipcoolingtech http://www.me.gatech.edu/featured_3Dchipcoolingtech mentions a DARPA effort to fund research into 3D chip-cooling technology.