Strange noises coming from PC: View Solution

This blogpost offers you methods/solutions to get rid of strange noises coming from your desktop PC 

The first step is to find the source of the noise. The most likely culprit, by far, is a fan in the system. The second most likely culprit is a hard drive. I have to tell you, I service PCs, and I have seen a very large number of PCs in which the bearings in genuine Intel factory coolers (for example, heat sink and fan) have gone bad, and these fans make terrible noises when cold (especially in the winter in northern climates) but become silent after warming up, and my first suspicion would be the CPU cooling fan. 

FANS

Almost all PCs have at least two fans, one in the power supply and one on the CPU, and they may have as many as seven or so (potentially add two case fans, a chipset fan, a video card fan, and in some cases a second power supply fan). The way to test a fan to see if it is the noise source is to stop it. While you could unplug one fan at a time, what I usually do is just stop the fan blades while the noise is occurring. If the fan hub is exposed, you can do this by putting your thumb (or a pencil eraser) on the smooth flat hub. Otherwise, I stop the fans by poking a “stick” into them. A screwdriver works if you are careful, but a non-conducting stick is better (a plastic stick, a pencil with an eraser at the end (but be careful of those with a metal band to retain the eraser) or even a “soft stick” like a soda straw can all be used. To stop the fan, poke your “stick” into the fan blades (it’s better to do this near the center of fan’s blades). For the fans inside the power supply, you have to poke the stick in through the air holes, and for this it is mandatory that the stick be plastic and not metal. You only want to test each fan to see if it is the noise source, so stop each fan in turn, see if the noise stops, and move on. Don’t keep any one fan stopped for more than 5 seconds, which won’t cause a problem for the fan or the item that it cools. If you stop the fan that is producing the noise, you will know it immediately. 

HARD DRIVE

If it’s not the fan, the next most likely cause is the hard drive. This is harder to test, but if the system makes the noise immediately at cold power-on, you should be able to tell if you disconnect the hard drive prior to power-on (obviously the system won’t boot windows that way, but it will still power up, and that should be all that you need). Pull both the power and signal (IDE or SATA) cables off the drive with the power off, then start the computer. In both of the above cases (fans and hard drives), the problem, if that is the cause of your noise, is bad bearings, and normally the solution is to replace the device. Usually this is straightforward, but you can run into problems, for example, if you have a bad fan on a video card (I’ve had to RMA an ATI video card because of bad fan bearings, when it would have been better for everyone if they had just been willing to just send me .... even SELL me .... a new fan, which in this case was easily replaceable and a $3 item). If it’s a hard drive, the drive maker will RMA the drive if it’s under warranty, otherwise you are out of luck. Sometimes you simply make a decision to “live with it”, and sometimes a tiny (TINY) drop of oil in the right place can fix the problem, but the first step is finding the source of the noise. It’s also occasionally the case that the noise is not coming from any mechanical source. 

MOTHERBOARD

If this is the case (e.g. none of the fans or drives are causing the noise), see if it’s coming from the PC “beep speaker”, which connects to the motherboard. Here, the test is to disconnect this prior to startup. This is usually easy on retail motherboards, but some OEM motherboards will combine the speaker connection in the same connector as other motherboard connections that are necessary to power up the system, which makes testing more difficult. You may also be able to test the speaker by using your ears to see if that is where the sound is coming from. Very rarely I’ve heard reports of pure electronic components making noises, things like memory modules. This is fairly rare, and I don’t have any suggestions for you in terms of either locating it or resolving it. However, I have run into power supplies that make continuous audible noises from the power supply itself (e.g. not the fan, but, actually, the high frequency switching transformers in the power supply). In this case, all you can really do is replace the power supply. Another possibility is that, in addition to computers, monitors have definitely been known to make audible high-frequency noises. These almost invariably come from the “flyback” (horizontal output) transformer, and if that’s the source, there’s not a lot that you can do, but changing the refresh rate or resolution might help. 

SPEAKERS

Lastly, the problem can be coming from the PC’s sound system and speakers (not the “beep speaker” connected to the motherboard, but the main speakers connected to the PC’s sound card or motherboard sound system). The test here is to disconnect the speakers, but if that is the source of the problem, then the culprit is more likely the sound card (or equivalent circuits on the motherboard) than the speakers themselves. But occasionally the speaker wiring will pickup electrical noise from another device, for example I ran into a situation where part of a speaker system was placed close to a UPS unit (uninterruptible power supply) and was picking up hum noise by magnetic induction from the large transformers in the UPS. Moving the speaker unit (or the UPS) six inches fixed the problem, but it drove everyone nuts until we found it (and once found, there was no doubt about the source). 

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 Courtesy of: CNT networks