PSU Fan Problem

[InsanelyNormal]

I have a problem with my PSU's fan. Very often, whenever I boot up my computer, the PSU's fan goes out of control and makes a lot of noise, as if it was going full power.

If I shake my PC slightly, the cooler calms down.
I'm not great with hardware, what do you think is causing the problem?

Thanks in advance.

Edit: The temperature is constantly around 40 degrees Celsius.

 

[Draqone]

Does the PSU fan slow down on it's own? If it doesn't last longer than 10 seconds I wouldn't worry.

 

[InsanelyNormal]

It doesn't stop on it's own, only if I shake the PC lightly.
Could the fan be out of sync or something? Or loosened?

There's also a slight rattling noise.

 

[Draqone]

Obviously, I can't tell if the fan is actually full speed or if it's a problem with the fan bearings. I am not able to say if it's a serious problem or not, the fan is not likely to instantly die though, so you are pretty safe to use the PSU until you find a replacement.