My computer is making annoying rattling sound

ambam

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Jun 5, 2010
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I think the cooling fan on my GPU is making an annoying rattling sound. Because when I turn the fan speed down to 20% the sound goes away.

Should I open up my case and blow into it with a can of compressed air?

How do I fix this?
 
1.) clean the fan
2.)spin the fan manually and see if the fan is hitting anything
3.)see if there is blades bent or positioned in an off angle compared to others
4.)perhaps considering getting a new fan?