Strange fan noise from my powersupply

Hello!
My powersupply acts wierd sometimes. Its a Corsair vx550w.
First of all, it sounds alote. I thought it was the CPU-cooler so i opened the chase of the computer to listen but i had wrong . I found out it was the powersupply that made these high fan noises.

The powersupply doesnt sound so much when your not doing anything powerful on the computer. Powerful things is like when I play games or use photoshop or any performance demanding thing.

But sometime the powersupply is acting wierd and the fan noise goes up even if I dont do anything powerful and the fan speed is not constant. The fans goes up and then down and back up again completely random and it sounds bad like its broken or something.

Is this type of changing fan speed on the powersupply normal or is it broken or something. My theory of the problem is that the powersupply gets to hot because these problems only appear when the temprature is high in the room just like it is in the summer.

Am i right or wrong ? hope its not a manufacture fault.

My computer specifications is in the signature

PS: My English is terrible. I hope atleast someone can understand something in the text , lol

I think the chassi is enough ventilated and i dont have so much dust, i recently cleaned it. My CPU tempareuter in load is around 50 degress Celcius and Idle around 30-35 degress Celcius.

yeah , totally agree on that!
All the flash/java apps and advertise is killing my PC , especially on the aftonbladet.se!

Hello!
Yeah , i have 3 120mm chase fans in my computer. One in the front, one at the side for the GPU and one at the back to force the hot air out from the chase.

I might think the computer stands on a very bad spot because of the fact that i have a very compact computer-desk.

But the strange thing is when the fan speed randomly goes up and down :S
Well, im gonna try to contact the Corsair support.

Thanks a lot for the help