Light clicking sound from PC - Not sure where from

Magus`

As the title states, there is an intermittent clicking/creaking/chattering noise coming from my PC. Best I can describe it is the sound a computer fan makes when it's partially obstructed. Problem is I have tested each and every computer fan I'm aware of (PSU included, assuming it has only the one fan) and it doesn't stop the noise. It's also borderline impossible to pinpoint the noise as it seems to be coming from the relative centre of the computer.

At first I thought it was my HDDs, so I disconnected them and it stopped.. at first. I have since separated the HDDs from the PC and listened to them and the sound does not appear to be coming from them. I started with the HDD because I was getting noticeable hiccups in WoW (hitching, basically). They have since stopped so.. yeah.

It's not the GPU as I've stopped its one fan and nothing changed.

It's not my CPU fan as I've stopped both fans at the same time and it doesn't change.

It's not my PSU fan because.. well you get the point.

I can only assume it's the PSU but for the life of me I can't think of what would make such a noise besides a fan. Not to mention the 'intensity' of the noise isn't consistent and even stops for periods of times. In fact the previous night it stopped completely and didn't start again until today. The main issue here is I'm not sure of a way to turn on JUST the PSU. I don't have the tools handy to un/reseat my CPU though I'm preeetty sure it's not making the noise. I need some type of computer stethoscope I guess.

The additional problem is I'm on a very tight budget and can't exactly replace parts left and right so it's pretty important I either find a way to fix this or, at least, figure out the issue. If it is, at worst, just a slight noise then whatever but I'm worried it's merely a prelude to something much worse. Any suggestions would be very much appreciated!

Foomy

Remove the psu from the computer, Turn off the power switch on the psu, then plug it into the wall. and then on the ATX power connector connect a short peice of wire to the pin where the green wire connects, there is only one green wire, and then a black wire next to it, doesn't matter which black wire. Now turn on the psu with the button on it.

Magus`

No sound coming from it. Hrm..

I'm gonna oil all the fans, just to be sure.

SyphonBlue

Do you have a Zip drive?

Magus`

I do not!

SyphonBlue

Damn, then I'm all out of ideas.

Foomy

Well if you've tested each component outside the case and found no noise, then the only thing I would guess is that a slight vibration from either a fan or a hdd is causing something in the case itself to make the click.

Maybe try tightening up all the screws you can find? or put the hdd on some rubber grommets?

That or you just have a village of invisible gnomes living in your case that spend all blacksmithing.

Magus`

It's actually stopped.. though I'm not sure why.

It didn't really start til the weather got cold, but Google isn't giving me much to go on.

The Wolfman

I've had a similar problem with the metal grill on my PSU fan. Sometimes at random, it'll make this ungodly rattling noise that sounds like something has gone catastrophically wrong. But it's just the metal rattling since I can lightly put my finger to it and it stops. Despite tightening and loosening screws, I can never dial into a permanent fix. It just comes and goes every few months. And almost always after I've left the window open in my room, which depending on the weather can make it pretty dang chilly. So it's almost assuredly...whatever the scientific term is called for metal expanding and contracting.