Ostriig on 26/6/2010 at 15:31

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And I don't mean funny haha. It's like this weird choppy hissing sound. It can be continously heard in moments of increased CPU activity, around the time the workload hits 30-40% and over on the processor, and also in very short (< 1s) bursts every now and then. For instance, now that I'm typing this and the Task Manager CPU meter is practically zero, I can't hear it except for said occasional bursts. But if I collapse to desktop and start waving the mouse around frantically, the CPU load will go well over 30-40% and I'll hear it clearly. If I start up a game or play a movie, the sound will again become constant, but slightly less hissing and more of a grind, almost like the sort you're used to hear from old hard drives. The hissing is also heard constantly and clearly when turning on the computer and when loading Windows (though oddly enough, apparently not while on the POST screen).

I'm pretty sure it's coming from the CPU. I've narrowed it down by powering on with both HDDs fully disconnected, with a different graphics card, and with the auxiliary case fan disabled, and in all cases the sound was still present. My proc is a three years old Core 2 Duo E6420 2.13Ghz with a stock cooler, by the way.

The temperature readings from Sandra are also batshit bonkers, here are the readings:
http://i211.photobucket.com/albums/bb67/Ostriig/processor.jpg

20 degrees?! I was worried yesterday when it was reading something like 30+, and now it looks like it's a progressive issue, maybe the sensor's gone? I'll check the BIOS and edit in those readings after I finish this post.

Edit: Ok, I dunno what Sandra's on about there. BIOS has only two listings for temps, CPU and MB, and they're both at a comfy 47 and respectively 41 degrees. Still, something has changed in some way or another, because I remember clearly that the CPU1 report in Sandra was around 30 degrees yesterday, and I also remember that it used to be aligned with the other (MB and Aux) temperature reports around 45 before that.

There's usually a good build up of dust in my computer, I don't clean it often, but I've just stuck the vacuum cleaner in there and cleaned it pretty thoroughly. Now, the only part of the CPU package that could make a sound is the fan, right? But then that would be exclusively based on the rotation speed, and how would the fan react so instantly to the changes in the CPU workload? Because the sound is instant, as soon as I do anything, even just scroll a Firefox page, it's there. Or could it be something else entirely?

Now, I've started noticing this sound in the past week or so, I believe. I've performed no changes to the system recently, aside from standard Windows updates. Other than that, same drivers, same BIOS version and configuration. It's also noteworthy that the system has suffered nothing in terms of performance and stability, it's still working perfectly.

Any advice would be greatly appreciated, this is really eating at me now.

Ostriig on 26/6/2010 at 17:23

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It didn't sound as if coming from the PSU. I guess my only option to test that would be to swap it out (though I don't have a spare), or just unscrew it and move it out of the case to see if I hear anything differently.

Nonetheless, how would that reflect the issue that it's only appearing when the processor spikes? The CPU going up in workload would put more stress on the PSU, and make it generate that noise?

Scratch that, you were right on the money, it's the PSU. Yanked it out, set it next to the PC and powered on, the hissing's definitely coming from it. So I suppose that's it then, higher CPU usage increases demand on the PSU, and causes this noise? Could it be heat related, summer and all, or simple wear and dust build up?

And the more urgent question - is it dangerous to the system, should I turn my PC off asap and stick to the laptop until I can get a replacement? Or is it something harmless that I can expect to go away once we go back to colder weather?

Ostriig on 26/6/2010 at 18:03

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Thanks Al, took a load off my heart! I'll look into changing it in the near future to be safe, but it's good to know it's not urgent. Between being strapped for cash at this point and my video card's specific power reqs, it's good to be able to take my time to find a replacement.

baeuchlein on 27/6/2010 at 16:40

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If it's just "singing inductors". There are other possibilities, probably less harmless.:ebil:

A hissing noise is sometimes caused by a failing capacitor ("cap"). I've heard that once from my brother's computer, where the failed capacitors were close to the CPU. Two of them had already emptied their bellies onto the mainboard itself, while the third one was just able to get the CPU up and running... sometimes. And it was hissing constantly. In this case, nothing else happened, although the mainboard could not be rescued anymore.

However, if a capacitor inside the power supply fails, there might be more damage, as far as I know. I think it would be a wise choice to disconnect the machine's power cord from the wall plug in times when it's not in use.

Yet another possibility is - surprise, surprise! - one of the fans inside the power supply. I've solved such a mystery just this weekend. One of my power supplies always made a noise like a very faint scream or a siren, changing with CPU load and temperature. Turned out it was the fan inside the power supply. As soon as I disconnected this fan (which was very easy in this special case), the noise stopped. When I connected the fan to another computer, while leaving the power supply unpowered, the noise was audible again.

Anyway... it's time to look for another power supply in your case.;) If you can't do it right now, ensure that the computer's power cord is off whenever you're not around. I think that will be enough.