With the Platinum Series Fanless 520 W, Seasonic has an entirely passive cooled power supply in its portfolio. For a passive cooled unit this device is everything but weak, since with 520 Watts you can power quite a machine. Furthermore this power supply received the 80Plus Platinum certificate, which means that at 50 percent load, the efficiency is above 92 percent.
Link:
http://www.ocaholic.ch/xoops/
