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A few months ago I built a new desktop using a barebones kit from TigerDirect. The specs are listed below.

It's been running perfectly since I fixed my previous issue.

A few hours ago, I was trying to compile the Linux kernel. The computer started making a very loud buzzing noise that sounded like the PC speaker. I tried everything I could to silence it in software, but it didn't work. No matter what I did, I would hear the buzzing noise on and off whenever I tried to compile the Linux kernel. I've compiled the kernel twice before on that computer, so I don't know why it was only doing it now. (I know that it isn't an issue with high CPU or disk usage, because I tried several other intensive things and nothing set it off. However, I do think it was a hardware issue.)

Other than issue, everything worked fine. I restarted the computer several times and it worked fine. However, the buzzing still persisted, so I decided to simply remove the PC speaker. I opened up the case, pulled out the speaker, and closed the case. Then I turned the computer on. The PSU fan started spinning, but the processor and case fans didn't, and the nothing showed up on the screen (so I don't think the processor was running at all).

I brought the computer down to the desk where I work on it, and tried running it again. This time, everything worked! So I brought it back and plugged it in again, but it still didn't work. However, I noticed that it was properly powering USB devices.

I brought it back down and opened it up again. I tried putting the speaker back in, but that didn't fix anything. Now, nothing at happens when I push the power button. However, whenever it is plugged in, the hard disk activity LED blinks periodically. I also hear a clicking noise when that LED turns on.

I'm guessing that it's a PSU issue, but I don't really know. Also, any guesses as to why I heard the buzzing would be helpful (though not nearly as important; I can live with buzzing).

The specs for this computer are:

  • Gigabyte GA-H55M-S2H motherboard
  • Core i3 530 CPU
  • 4 GB DDR3 RAM
  • 1 TB SATA hard drive
  • 500 Watt PSU
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3 Answers 3

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Sounds like a PSU to me. PSU problems can sometimes be weirdly intermittent and they can cause almost any kind of strange behaviour in a computer. PSU problems can also produce weird noises. I have a cheap PSU tester that comes in handy in these situations. I'd be inclined to just replace the PSU, because a) any testing you do is going to be inconclusive since the problem is clearly intermittent; and b) a bad PSU can take out a motherboard - easily. By the way, just moving the computer may have bumped things around enough to affect what happens when you power up. If it wasn't a computer, I might even recommend "percussive maintenance" - the fancy name for giving it a good whack.

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I found a multi-meter and tested the PSU - it was definitely bad. It was still under warranty so I got it it replaced. I haven't put it in yet so I don't know if any other components were fried by the old PSU, but at least I know that it was definitely the PSU that was causing the problems. –  Zifre Jul 19 '10 at 0:52

Does (did) your computer normally beep once on startup? Is there any evidence on the display that the computer is POSTing?

I would check the power supply. You could swap it out, but if you have a multimeter and a little know-how it's easy to test in place. About.com has instructions on how to do this. If the power supply is preventing your computer from starting, it'll probably show abnormal voltages or outright missing voltages immediately.

If the PSU isn't the trouble, it sounds like the mainboard to me. If you can find a POST analyzer, use it. It's probably not worth buying one, though, unless you're really curious -- The downside to a POST analyzer, of course, is that if the problem necessitates using one, the device will virtually always just confirm to you that the mainboard will need to be replaced.

Before going to the expense of replacing the mainboard, strip down the system as much as you can (remove dedicated video cards and use integrated, etc) to try and narrow it down to the mainboard. Swapping out parts with known good units will help to narrow down the problem - in particular, be sure to try swapping out the RAM. In theory it should visibly fail POST if the RAM is bad, but I've seen stranger.

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It normally does beep for POST. It does sound like a PSU issue at this point. Unfortunately, I don't have any extra parts that I can swap in, and I don't have a multi-meter... :( –  Zifre Jul 10 '10 at 13:03

Some PS components can make a buzzing sound, but it isn't a good thing if they do. Fans can also make buzzing sounds. Also not good.

If the PS is making the noise, or possibly even if not, the problem could also be the power source. Some (most / reasonably priced) UPSes, when on-battery, output a stepped (approximate) sine wave instead of the pure sine that you get from the power company. Some power supplies (notably high-efficiency PSes in my experience) don't operate with that as input, and some could conceivably (though I haven't seen it) make noise due to this.

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I don't use a UPS (just a surge protector), but I guess that the buzzing probably was the PSU... –  Zifre Jul 10 '10 at 1:24

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