Antec Earthwatts 500 Question

[nwo4life022]

I just bought this power supply yesterday and im wondering about a noise coming from it. It seems when i first power up its fine but when i start booting into windows the sound starts when the hard drive activity makes noise. Its not really loud but i have extra sensitive ears and just wondering if this is normal sound or if something is wrong. Its like the power supply is having activity like a hard drive would and it squeels up and down. Sorry for the explanation i wish i could let you guys hear it but im just worried that it may be bad or maybe im exaggerating and its a normal sound.
Any advice would be great cause im debating weather to bring it back and put my xclio goodpower back in. Only reason why i bought this one was i got it on sale Btw the xclio didnt exhibit this noise