I've got a about 2 1/2 years old 235 watt PSU in my computer. Lately it has a strange noise inside it, almost like the fan is hitting a wire or something, like a rattling noise. After a while the sound stops and my computer sounds as usual. It doesn't occur all the time, and sometimes it happens while the computer has been switched on for a while. I checked the PSU by removing it from my computer and see with a flashlight what exactly happens, but I couldn't see a thing. I am a little afraid to open it completely to have a clearer view, because maybe I will get 220 volt shock when I accidently touch something. My computer is working fine, and all the fans are rotating as they should do (inclucing the PSU). Is it harmful to continue to work on my computer or can I damage any components in my computer (except for the PSU) if I continue? OK, other question. Are all the PSU's the same? The PSU which is inside now, is from Packard Bell and it is a normal ATX. Can I replace it safely with another PSU, without worrying about not fitting parts? Thanks in advance.