if you have been experimenting with silent computing for a while, you probably already know that cheaply made, OEM 40mm could become the loudest single components in a case. heck, even if it was a decent fan, 60mm or smaller fans are loud by nature, just because of the ridiculous RPM that they spin at.
of course, it is assumed that you already were thinking about replacing it with a passive sink. zalman, perhaps?
but there is another $20, and it could even involve a little modding.
decisions, decisions...
i hope you find an answer to this. I have found that reviews of mobos never seem to mention such mundane details such as chipset fan, and when they do, its with useless terms like "pretty quiet". sure, it's pretty quiet... with 4 wd raptors buzzing, while burning a DVD and using 4 tornado case fans at 12v. i bet some users at SPCR would know.