[CentOS] diagnosing noise

Though quiet at the moment,
my desktop sometimes sometimes makes a noise that I attribute
to either a disk or a fan on its last legs.
I'm looking for suggestions for distinguishing.

For the disk, I expect I should use either hdparm of fsck.
Even after reading the man page, I'm not sure how I would use hdparm.
If I use fsck, what should I take as evidence of a bad drive?
A good drive?

Is there a way to tell whether the OS thinks a fan is on?
Is there a way to turn a fan on or off manually?


Time for a backup.

-- 
Michael   hennebry at web.cs.ndsu.NoDak.edu
"Sorry but your password must contain an uppercase letter, a number,
a haiku, a gang sign, a heiroglyph, and the blood of a virgin."
                                                              --  someeecards