A puzzling problem has been plaguing my PC the last two days; better start at the beginning...
Before I start, I should mention that I haven't installed any new hardware since November (a DVD±RW). My system is an Athlon XP 1700+ on an ECS K7VTA3 motherboard with 1GB RAM, a GeForce 4 ti4200 and an 80GB Maxtor hard disk. It also has some other things like a C-Media sound card, modem, ethernet controller and TV tuner.
Two days ago, I began to hear a whining noise coming from my computer. I thought maybe the fans were clogged with dust, so I decided to take everything apart and do some dusting. I evicted a huge cloud of dust, mainly from the CPU fan and the inside of the power supply unit.
After putting everything back together, I found that not only had the whining failed to go away, but it had got worse (or maybe it just seems to get worse the longer I listen to it?).
Now I have a loud high-pitched whine, just on the cusp of hearing (it must be getting close to ultrasonic), which is slowly driving me insane...
After some poking around, I decided that the sound seems to be coming for the power supply unit (a 300W unbranded PSU that came with my case.)
After a bit of searching around on the web, I read that power supplies (and other things) start to whine when they are starting to fail, and that the sound in this case would come from one or more 'whistling capacitors' that are breaking.
I happened to be visting a friend with a lot of old computer gear anyway, so I brought the PSU along to see if he had a spare. He had an old computer that wasn't being used anymore, which had a 230W PSU, so I thought I might try that. I decided to put my old CPU into that computer to see if it would whine there, which it did. In fact, it whined the moment I supplied it with power, whereas in my own computer it only whines when the computer is on.
Anyway, I brought both PSUs home with me and tried the 230W one, which immediately started to whine as soon as I supplied power, even though it had been fine in the computer that it came from.
After some thought, I decided to try the PSU from another 'good' computer that I have access to. This one has a fairly new Mercury 400W PSU which should be working perfectly. However, when I plugged it into my computer and started it up, it soon started to whine too. Of course it's nice and quiet in the computer where it comes from.
I tried taking everything out of my computer: the expansion cards, GeForce, IDE chains, even the CPU fan. Turning on the computer in this minimal state (only motherboard and CPU), the sound is still there, but it was different, a sort of high-pitched electric crackling noise which sounds a bit like a fan, but the noise persisted even if I stopped the PSU fan by blocking it.
The noise seems to get worse when everything is connected, leading me to think it might be related to the amount of power the computer is drawing.
The sound also gets slightly louder when I hold down a key on my keyboard or use the mouse wheel to scroll up or down in Opera...
I also tried my PSU in the 'other good computer' I mentioned earlier, and it works perfectly without a single sound other than the normal fan whirr.
So, basically any PSU I plug into my computer makes a sound (though each makes a somewhat different one), and plugging my PSU into another computer makes no unusual sound. The PSU also sounds fine when it is powered up on its own (without a computer attached).
I'm 99.99% certain that the sound comes from the PSU, though. The only thing I can think of is that maybe the motherboard is drawing a huge amount of power for some reason, and the PSU makes the whining noise as it struggles to meet this demand.
Another possibility could be that the part of the motherboard that controls the PSU is damaged...
I really can't think what else to do. Any suggestions?
PS: If anything I just wrote doesn't quite make sense, I blame it on that high-pitched whine driving me insane!