I have a video of the problem here. Please turn your volume down before 47 seconds into the video; the noise is quite loud (the volume in the video isn't even as loud as it sounds in real life from that distance from the case!)
Basically: something in my computer makes a LOUD, constant, very high pitch (around 20 kHz? near the upper range of human hearing) alarm-like sound. It's loud like a smoke detector, but very directional. I was surprised to learn that nobody downstairs in my wood-frame house could hear the noise (usually we can all hear what everyone else is doing, but that's with much lower pitched sounds). It seemed a bit of an odd frequency for an alarm: my dad, who has upper range hearing loss, couldn't hear it at all, even in the same room!
The noise first happened while I was sound asleep in the middle of the night, with my PC powered up under my desk in my room. I quickly determined the sound to be coming from the PC, and in a moment of dazed stupor, I thought it could be a component overheating — certainly not something I want — so I killed the power and unplugged the cable from the PSU. I gave it a rest for a few days: to let it cool off, to research my problem, and think about how I was going to approach a solution, rather than rushing headlong into trying to fix it. I was also busy with other stuff in life so I didn't have time to worry about a downed PC, and used an alternate computer meanwhile.
Skip ahead a few days to when I start to troubleshoot it…
My initial problem is I'm having a hard time isolating exactly which component in the case it's coming from. It's so loud that I can't detect a directionality, and I have a LOT of components, so as far as I can tell, it could be the motherboard, the CPU, one of my two video cards, the RAID card, the sound card, or one of the hard drives. That doesn't narrow it down a whole lot, does it?
I tried blowing 548 cfm (cubic feet per minute) of air directly into the open case of the PC, thinking it could be a cooling issue or perhaps a dust obstruction. Dust went flying EVERYWHERE when the large room air circulator first spun up and started spewing a powerful current of air into the case, but other than that, the problem persisted. I checked every fan I'm aware of in my case, as well as the PSU fan, and each GPU fan, and all were spinning.
So the fans are spinning, and I severely doubt anything is overheating, because all the dust went flying out of the case the moment the air circulator's powerful fan came to bear on its innards; furthermore, with the air beating down steadily on all the components, I'd wager this system could operate fine even if all of the fans inside the components were to suddenly die.
So now what? How do I figure out what's wrong? Read my answer to see how I figured it out.
Best Answer
I decided I would bear the awful alarm sound just long enough to turn on the PC, get to the BIOS, and read off some of the sensors to see if I could discern from them what might be the issue. I would look for red flags like: high core temperature; SMART warnings; low fan RPM (or high, even; anything unusual). I powered it on -- a risk, because I had no idea what the problem was, and it might've been worsened by trying to operate the system -- and waited.
The Option ROM for my Adaptec 6405E spun up as expected, taking several seconds, and I thought it was odd that the high pitched noise hadn't started while the RAID controller was "Booting the Controller Kernel" (which takes 10-15 seconds). But then it started -- right as the RAID controller displayed on the screen, a warning that my RAID array was degraded. Aha!
So I had found the problem quite clearly: my Adaptec 6405E RAID controller was emitting a loud alarm to let me know that my RAID array was degraded, likely due to one of my four hard drives starting to die.
The permanent fix here is simple: I have to identify which HDD is failing, and replace it before my RAID-10 array dies completely. The safest way would be to stop using the computer until the replacement HDD arrives.
But I wanted to keep using the system, confident that the pair of brand new hard drives in the array could hold up for a day or two while I got the replacement disk (the disk that failed is several years old). So I had to figure out a way to shut up the alarm!
The driver you download from Adaptec's website has a command-line tool called
arcconf, which I've come to love, due to its immense power. To shut off the alarm, I ran this command in an Administrator command prompt on Windows:arcconf setalarm 1 silence.silencetellsarcconfto stop notifying me about the current problem; but if another problem is detected, it'll alarm again. I don't want to set the alarm tooff, because then I won't hear it in case my RAID card is trying to tell me that another disk is failing, or perhaps the card itself.I'm going to make light use of my system while waiting for the replacement disk, confident that my new pair of disks will be alright for basic web browsing until I get my redundant RAID-10 configuration back. I hope this answer helped you learn how to troubleshoot the possible source of an alarm coming from your computer.