Found this link in Knowledge Base but haven't checked it out yet. Allows selection of 3 0r 4 pin fans in BIOS. http://support.asus.com/Search/KDetail.aspx?SLanguage=en&no=F5BEB653-FDA2-4DD2-50CB-D6378F99E630&t=2Post if it is the solution!

I will be testing the chassis fan and asst fan headers shortly. Hopefully this afternoon to see if a rumor I heard is true or not. I was told that SOME of the chassis fan controllers could be +12V Voltage controlled and would not require the 4-pin PW...