It could be that if the board was designed with sale in both the retail and OEM/Enterprise channels, that a "complete solution" in their enterprise channel would include 6 pin temperature monitoring fans. They probably wouldn't sell the fans in the retail channel but made sure the headers worked for both so they could sell one series of boards for all sales segments.Thanks for the replies. Weird that they added additional pins when there don't seem to be any fans that support using them - especially on a board so cramped for space.