Really glad I found this post. I'm planning a build with the FC8 Evo and this thread has given me better info and pics than I've been able to find anywhere. Was originally planning on going with the Wesena ITX5 but really want to see if I could use the passive features of this case.
I plan on using an undervolted Core i5 3570k. The new 'Evo' model supports up to 95w thanks to a new CPU block, and more heatpipes (with a new design) so an undervolted 77w should be perfectly fine.
What worries me more, is the video card. There are zero ventilation holes on the side where the video card will be. In my opinion this would've made a giant difference in the types of cards you could put in this case.
Nonetheless, I'm going to risk putting in an AMD HD 7750 (with fan) and see how it goes. It's roughly half the TDP of my HD5770, but double that of the HD 6450 in your build, so I'm a little nervous. I think the fan should make a big difference though. A passive heatsink in such a tiny enclosed area would just stew in its own heat. I have a few other ideas to reduce heat as well but I'll wait til I run tests before entertaining them.