Something's started squeeking

[LCADolby]

When my PC loads new web pages, new pictures in the viewer or when flicking through, a constant squeak accompanies these things and many others.
When the process is pretty busy like flicking through the pictures in the viewer quickly the squeak gets a little louder and higher pitched.
 
All my PC parts are now over 4 years old and have pretty much only been turned off for a total of 2 weeks in that time, the question is what parts are most likely to be the creator of the squeeking?

[FLS]

I would look at the fans first.

[The Fugitive]

Most MB have utilities to adjust your fans speeds. Crank them up and see if the sound changes. To me, as you call for more pictures and stuff to display it sounds like your calling on the hard drive to find these things. If thats the case it could be the HD making the noise as it searches the disk for the info your calling up.

[FLS]

If it's the HD you may hear it at startup too.

If you hardly shut it off for 4 years it may be dusty in there.

[Bizman]

I always suspect the hard drive after three years or so... The optimal conditions for a non-stop running one is about 40 centigrade, not so easy in the summer! Wouldn't do any harm to get a new one and make a clone out of the old one to see if the squealing would end with the new one. If that weren't the culprit, you'd have a new hard disk for your next build ready.

Fans have already been mentioned. Open the case and carefully stop one fan at a time to find out if any kind of strange noise stops. For fans you can't reach, just listen closely. You might also like to look at the Task manager to see some explaining spikes in processor usage while flicking through pictures. A spike in the CPu usage also means a spike in heat producing which causes acceleration in fan speed.

[LCADolby]

Thanks gents, I'll have to have a good at the fans and HDD closely 

[nrshida]

Arthritis 

[Chalenge]

Hmm, I would suspect the fan on the video card.

[LCADolby]

I cleaned out as much dust etc. as I could today, the squeeking seems to be coming from the power supply area.
I wonder if is the cause of my blue screen on start up problems. :/

[Skuzzy]

If the fan is not making the noise in the power supply, then you have a leaking capacitor.  If that is the case, then it is only a matter of time before it fails.  And it would be a short time.

[LCADolby]

Leaking capacitor?

So I'll be expecting a pop and full loss of power soon?

[The Fugitive]

Leaking capacitor?

So I'll be expecting a pop and full loss of power soon?

...if its not the fan, yes. You can check by sticking something in the vent to hold the fan blade and start the computer up. If you still hear the noise it could be the capacitor, if not, its the fan.

[Skuzzy]

A "leaking capacitor" in this context, is one that has been breached and current is arcing from the breach to a nearby conductor.  Typically, you will smell ozone, unless the leak is really small.

Yes. those leaks make noises.  Sort of a high pitched buzzing sound, which can come and go, depending on the charge state of the capacitor.

[Chalenge]

Dolby, if you even suspect your PSU is going bad you need to replace it before you ever turn it on again, or risk a total system loss every time you do. Just the way I look at it of course.

[LCADolby]

What does ozone smell like?

I stopped the fan and it kept squeaking, it has to be a capacitor.. I'll see if I can get it looked at by a pro tomorrow.
I'm hopeing it wont be too expensive a fix, as money's tight around here.