CPU fan makes a really loud noise when it spins.?

Before you mess with the fan you better look under task manager and performance to make sure your CPU isn't running wide open because of some virus or malware.

Next loud noise? As in spinning fast or as clattering and squealing from a bad bearing?

OK determine the last two things first .get back to me! And I will tell you what to do

A noisy fan is either a faulty bearing or possible a cable that is catching on the blades. If the fan blades are clear then replacement is the only option.

Update your post with make and model of processor and what sort of cooler you have installed or take it to a tech

Fan makes a noisewhen spinning when it:

1.loose

2.blades bent

3.bearing is bad.

#1 and #2 you can fix yourself. very easy. #3 the only fix is new fan.It is also easy to do,but you need to buy new fan.

Your CPU temp, is too high, so the fan must make up for it.