Intel D510MO Mini-ITX Motherboard Review
 

The most appealing thing about the Intel D510MO Mini-ITX motherboard with 1.66GHz Intel Atom dual core processor was that it could be used as the core of a completely silent system. Since the board is passively cooled, you can pick other passively cooled or solid state components for a build that generates absolutely zero noise.

http://www.bigbruin.com/content/inteld510mo_1