Problem with a fan

[bosschester]

I have a unit fitted to my motherboard with a 12v fan attached.
Could this unit be the CPU? - sorry, I'm not very knowledgable about these things!
Anyway. The problem is that the fan isn't working well. It has a label on the front saying that it is an akasa and mentioning ball bearings. It sounds as though the bearing has collapsed. Very noisy!
When I boot up it runs quite well at first then the unit behind gets very hot and the pc switches off.
Is it a difficult job to replace the fan?
Is the unit which overheats the CPU?
Can the fan be purchased separately?
Is the unit likely to be damaged?
Any assistance would be appreciated

[ChuckFickens]

Yes that is the CPU by the sound of it.

Make sure you have cleaned all the dust out from the fan and the heat sink it is attached to, if it's still noisy after a clean then yes you need to replace the fan, these can be bought separately.