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Computer whining (~16khz noise coming from somewhere in the case)
My computer makes a very annoying high pitched noise under medium loads. I have been chasing this problem for a few days now and would appreciate any input you might have.
System details: OS: Lubuntu 21.10; CPU: AMD FX-8350; Mobo: Asrock FX990 Ext.4; GPU1 MSI Geforce GTX1060 6GB; GPU2 ATI Radeon HD7750. Will elaborate upon request.
See the constant 16khz tone on the far right? that's my problem:
The noise usually appears after playing KSP for about 30min-1hr, with some other stuff (usually a youtube video) going in the other monitor.
Things that I think are NOT the cause:
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My audio setup. I've turned off the speakers, unplugged them, moved wires around, all with no discernible effect.
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The CPU fan. I've gone into BIOS and throttled it up and down manually. I can see the RPM readout changing but the noise does not appear, even at max RPM.
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The GPU1 fans. I went into Nvidia Xserver settings and throttled them up and down without reproducing the noise.
I can't say I've encountered a problem that makes using my PC physically painful before. Please let me know if you have more troubleshooting ideas.
2 answers
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The following users marked this post as Works for me:
| User | Comment | Date |
|---|---|---|
| Darth_Muldoon |
Thread: Works for me I disassembled the power supply to poke at inductors and capacitors like Olin suggested, but I can no longer reproduce my issue. I guess breaking the w... |
Apr 10, 2022 at 19:43 |
This is from a meta-stable oscillation of one of the switching power supplies. The switching speed is almost certainly much higher than this, which is why you don't hear it most of the time. Under just the right conditions of input voltage and load current, the control algorithm of the power supply oscillates at 16 kHz.
This is not necessarily a problem electrically. Most likely the resulting voltage is still within spec. The only real downside, as you have found, is that it makes an annoying noise.
There are three mechanism by which a circuit with varying currents or voltages can cause mechanical vibrations, which is what we hear as sound:
- Every little bit of wire wound around a magnetic core experiences a sideways force. Electric motors, generators, and loudspeakers work on this principle. Wire is usually held quite tightly in inductors, but nothing can be held absolutely rigid.
- By magnetorestriction. This is the property of a material that causes it to change size as a result of an applied magnetic field. The ferrite in the inductors used in the switching power supply was selected in part to minimize this, but some amount is always present anyway.
- By the piezoelectric effect. This is the property of a material that causes it to change size as a result of an applied electric field. Quartz crystals exhibit this effect enough to be used in some types of microphones and small earphones. In your case, it's material in the ceramic capacitors that is causing the problem. The ceramic changes size slightly as the voltage on the capacitor changes. Unfortunately, the types of ceramic that allow for smaller capacitors of the same capacitance also exhibit the piezoelectric effect more strongly. Whining is therefore a tradeoff with cost and board space, so shouldn't be much of a surprise in a consumer product optimized for low price.
The component itself may not actually be vibrating much. Due to it being rigidly mounted to the circuit board, it gets the whole board vibrating, which then couples much better to the air to produce the sound that you hear.
Try touching inductors and ceramic capacitors near any inductors on the main board when you hear the whining. You will probably find some places where touching changes the sound.
After finding the offending components, you might be tempted to dampen the sound by putting hot glue or epoxy around the component. Be careful with that. You can easily add thermal insulation to components that need to dissipate heat. That may cause the components to fail under high usage at high ambient temperature.
Do not poke at the large capacitors inside the PSU with your fingers! This is dangerous even though the power has been removed.
Right, which is why I said to touch near any inductors on the main board. Everything on the main board is limited to low voltages.
In case you aim to poke at components on a circuit board with your fingers, it's very important that you first touch some non-sensitive part of the board, such as the metal frame around the connectors. Otherwise ESD might break the board.
Good point.
Olin's answer correctly diagnoses this as a form of coil whine, which can be emitted from almost any component but in your case is coming from the PSU.
If you're not comfortable with voiding the warranty and touching potentially high-voltage components, the simpler (but perhaps more expensive) option is to try a different PSU. The amount of whine you get from any given device can vary considerably based on the make and model, and is typically less (although not necessarily silent) on more premium components.
My current PC came with a fairly basic Cooler Master PSU which was so whiny the machine was practically unusable, but the noise all but disappeared when I replaced the PSU with a more expensive Corsair gaming model. Of course you need to decide how willing you are to spend money on a new component without knowing up front if it will solve the problem, but if you order it online you should at least have the right to send it back for a refund if it doesn't help.
Clarification in response to comment: my answer is not that Cooler Master PSUs are always noisy or that Corsair PSUs are always quiet. Both are respectable brands with a range of products at various difference price/quality points. My suggestion is that if you have a particularly noisy PSU and are prepared to spend some money, then upgrading to a more premium model (possibly one which is specifically sold as "silent" or "quiet") might solve the problem, as it did for me.
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