Strange vibrations on p183

[BadOmen]

For a while now, I've noticed that even when the PC is off and unplugged, if I slide my hand on the side of my case, I can feel some strong vibration. It doesn't make any sound when I leave it alone, but if I run my hand through its side panel, it buzzes loudly at the touch.

The computer is on top of a large bedside table. On its bottom shelf is an APS battery backup, and that's it, there's nothing else inside or on that bedside table, or touching it.

To make things stranger, I once moved the unplugged PC to another table, and the vibration could still be felt. My forehead slightly touched the internal metal part of the case accidentally, and I felt some kind of shock.

Has anyone seen something like that? Would that be dangerous for the components?
thanks in advance

 

[CurseTheSky]

It sounds like you have a cable shorting out somewhere, but the fact that it's unplugged and still doing it would make me very concerned.

You may want to CAREFULLY check your PSU with a multimeter. If there are capacitors that are holding a charge for a while after it's turned off, and it's causing some kind of oscillation or vibration + a short causing a shock, that could spell disaster.

 

[BadOmen]

You may want to CAREFULLY check your PSU with a multimeter. If there are capacitors that are holding a charge for a while after it's turned off, and it's causing some kind of oscillation or vibration + a short causing a shock, that could spell disaster.

Thanks for the input. The PC has been working fine, in general. Got some blue screen problems a month ago after I/O failures, but other than that, nothing wrong.

Now, I have never used a multimeter, but I take it that would require the PSU to be opened, right? I don't see those pins testing SATA molexes.

In order to rule out vibrations coming from the APS, the floor or God knows where, should I try to place the computer on top of some isolating material? Which material would be good? Could styrofoam make a difference, or does it have to be rubber?

EDIT: Another curious fact: right now the PC is on and the vibration can only be felt at one side panel. All other external parts are ok.