I got a new power supply (480W) and replaced it with the old 300W but, the new one is so much noisy could I solve this or I have to return it to get another one ?

You can't solve it. Return it if you can. Check the PS at the store if it isn't too loud inside and see if the next one is noisy. I read it wrong and answer it wrong too. So get off my case you peanut.

Post the make model of the PSU. How much did you pay for it?

Different PSUs have different noise levels. Furthermore, the fan or fans in the new one isn't the same as what was in your old PSU.

Return it to get another one.

in the main this seems to relate to the quality, or lack of, that people pay for. On one I had i dismantled it and connected the fan to the 5 volt output instead of the 12volt output, it ran at a resonable speed but was much quieter. It seemed to be fine, but there is always the chance the cooling might then be inadequate. Also you should NEVER open up a PSU unless you are experienced in electrical stuff as it can be dangerous.

It's a very cheap one, I don't think it makes trouble for the power it's noisy but, the fan is so fast, the temprature is cooler than the old one I think. The sound that comes is like Fan's edges is touching something else. I tried to use compressed air to see if the sound comes from the fan if turns arround, actually, I hear the same sound, that means something is touching the fan edges and that's why noise is coming.