I got three mobo fans pluged in now if i pull one out the one fan spins normal rpm but when i plug other fan in it spins very high rpm.Two fans are coolermaster other two fans corsairs,Both corsair fans pluged into mobo other coolermaster pluged also into mobo and other coolrmaster is pluged in as molex.The two corsair is top mounted sucking air in over cpu cooler.It is the corsair fan spining high when the coolrmaster fan is plugged in