VIA EPIA PX10000 Pico-ITX - Mobo size of Hand
 

The EPIA PX 10000 is the first motherboard from VIA Technologies to be released in their 10cm x 7.2cm 'Pico-ITX' form factor, and is currently the 'world's smallest full-featured x86 mainboard designed for ultra compact embedded PCs, systems and appliances. When idle the PX drew around 14W. Even after extreme CPU load (running Prime95 for an hour) we couldn't get this figure above 16W.

http://www.mini-itx.com/reviews/pico...ult.asp?page=1