What is the quietest computer tower case?

The quietest computer tower case is one containing a computer system that is cooled passively. Without case fans a system is almost noiseless. Hard drives and optical drives will make a little bit of noise when their internal parts are moving.

Tom's Hardware caters to hardcore gamers who are into serious overclocking. Good ventilation, airflow, and cooling are important factors for them and that means using case fans. Sometimes they use lots of case fans. It's the movement of air through, over, and around pc components that generate sound.

There is a growing group of pc enthusiats who are into home theater pc's. Some of those pc's are quite small and use passive cooling. I've seen a few beautiful custom wooden cases. There is no noise. They are definitely not cases or systems for hardcore gamers.