The bearings wore in their old orientation.
Since the force is applied differently,
the play in the worn bearing is showing up as noise.

You need a new fan.  After a bearing is noisy
it is too late to oil it. (Waste of time.)

Rick Glazier

From: "aung-maw" 
> Dear Kenneth,
> 
> After replacing new Motherboard, it found CPU fan being very noisy (or, it 
> may be higher speed than before)
> The only difference between old MBD and new one is that Fan position 
> (initially mounted vertically and now horizontally)
> 
> Do you see any problem or unusual of this noise? any solution.

                  Visit our website regularly for FAQs,
               articles, how-to's, tech tips and much more
                          http://freepctech.com