Make your Entire Case a Massive Heat Sink
Ditch your case, take your heat sink, and build onto it until it surrounds your computer (or something along those lines). Basically, you can build a computer so that it will dissipate all it’s heat throughout the case walls, instead of internally.
I have wanted to build a fully passively cooled computer case since I had my first Athlon Thunderbird 800 MHz. That time the fan noise was amazingly high, and manufacturers didn’t much care about the noise levels, and didn’t offer products for building a quiet PC.
