According to this posting, my Linux-computer ‘Phoenix’, which is also my Web-server, once had a failed case-fan, and I had replaced it with a new one.
I knew that the old one had failed, both because my desktop widget showed it as only spinning intermittently, and because when I inspected it, with the tower-case open, I could sense with my hand, that the old fan had increased resistance to being turned. I assumed some sort of bearing failure.
The new case-fan did spin at full speed correctly, for some time.
But in recent days, I find that the new case-fan has failed again. I really have no explanation for this, but my widget now shows its RPMs doing the same thing they were doing, for the old case-fan, sometimes spinning, and sometimes stalled.
Now, I could undertake simply to replace it again, with a 3rd fan. But since the first repair did not work, I have no reason to assume that replacing the case-fan again would work. And so I am left pondering, what I should do.
(Edit 05/20/2017 : )