recently from few days my pc makes loud noise (power supply fan is making loud noise at startup)

however, noise lasts for few minutes only and then it runs normal........

i searched on the internet and found that its because of the dust accumulated near the fan........
i tried to clean it with the help of blower, but didn't succeeded.......

i m sure the noise is coming from the smps (power supply)

is this because of dust or something else?