My homebrewed ultraquiet pc’s powersupply had a meltdown over the weekend due to the heat. Following advice from silentpcreview, I got the machine noise down to around 20db, which is the equivalent of someone whispering from five feet away. The box was actually quieter than my Powerbook at this point. But five months later, Summer has arrived here, so it looks like all that fan undervolting will have to take a backseat until the weather pattern gets a little cooler.