Intel(R) QST is designed to minimize overall system acoustics and psycho-acoustics, while still maintaining thermals below reliability limits. If QST is slowing the fans, then there is no need for the additional cooling that the fans could provide. If temperatures reach levels that require additional cooling, QST will speed the fans at that time. Slowing the fans saves power. There is no performance or reliability penalty slowing the fans. I simply cannot fathom why anyone would want their fans to be running at full speed all the time. To each his own, I guess. QST can be disabled from MEBX. There are a couple of threads that explain how to do this. Understand that, if you disable QST, you lose your monitoring capability as well; heaalth monitoring and fan speed control are all implemented within QST. While some temperatures may be monitorable from software, many cannot be seen without QST as they are in devices on auxiliary busses...
I would keep my fans running at 100% simply to keep the unecessary higher CPU temperature down. Why would you allow more heat to build up rather than use the already equipped fan at a more efficient speed?