My pc used to startup quietly, after a very hot summer and with the arrival of the cold weather of autumn with rain and moisture, it started making a very loud noise during 2 minutes (or so) at startup and on the first boot of the day, then it quiets down and runs normal, fan doesn't make any noise at startup when the computer is already on and i turn it off and then power it up again (warm boot), then i decided to check the fan speed on bios or hw monitor software, my surprise, since this fan is not controllable (3 pins) and always runs at 100% at 1900 rpm, bios or hwmonitor reported 1200 rpm on startup, then progressively the speed increases until 1900 (1200 - 1250 - 1400 ...) once reaches 1900 noise is gone and runs normal and silent, this is very strange and different from what other users with similar problem report since my fan doesn't start at 100% RPM what suppose to, starts at lower speed and makes noise because of that, my first thoughts is fan rotor failing, but i really don't know, should think about a new fan? Any thoughts?