Not so sure
I have purchased a small form-factor PC - but it wasn't much to do with the form-factor. Because small form-factor PC's use much lower-powered parts, it was a fan-less PC and is almost entirely silent. In fact, switching it on for the first time was disconcerting. Other than a light coming on, nothing happened for a few seconds. The only noise it ever makes is when the hard disk spins up.
But this is why I bought it and I know plenty of people for whom squeezing the last GHz of performance from their PC has become secondary to making it as quiet as possible.
