when is coil whine. Not coil whine? & how do you find it?

Thread Starter

Teljkon

Joined Jan 24, 2019
267
Hello. My computer has suddenly begun to give a EEEEEEEEEEEEEEEEEEEEEEEEEEEE sound even when off. Probably not the processor not sure if it is the GPU or PSU. How would I go about finding this. I mean I guess I could get a mechanics stethoscope. What would be the better method on the component level after i crack open the offender? Is it always a coil or could it be a capacitor? I also have a Xbox Controller that just decided to die last night. When it rains it pours I guess.
 

MrSalts

Joined Apr 2, 2020
2,596
If your computer does it whil powered down, I assume it is a desktop and an ATX power supply. The ATX has a 5v standby pin that is always powered. The rubberized potting compound that "glues" or dampens the effect is likely inside the power supply. Look for coils around black ferrite cores. These may be the culprit. They aren't necessarily "bad", just try adding some "metal safe" silicone caulk or siliconized latex caulk between the wires and the blackish ferrite to avoid any scraping/ whine as the ferrite changes size ( slightly) with each cycle of AC or of the SMPS circuit.

You could try swapping out the ATX power supply with a known quiet one in case you are unsure. Then try to isolate which unit inside the ATX.

Also, there may be nothing you can do about it. Just a design issue. Did you recently add a high current load device like a video card or a motor driver of some sort. The extra load may be pushing the power supply near or nearer to its limit which causes the whine and nothing can be done about the noise other than getting a higher max wattage power supply so you don't have to work it past 50% of max load or so.
 

AlbertHall

Joined Jun 4, 2014
12,187
Even if a coil is making the noise the cause may not be a defect in the coil. It may be the circuitry driving the coil with the wrong frequency or an irregular, unstable, frequency.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
267
If your computer does it whil powered down, I assume it is a desktop and an ATX power supply. The ATX has a 5v standby pin that is always powered. The rubberized potting compound that "glues" or dampens the effect is likely inside the power supply. Look for coils around black ferrite cores. These may be the culprit. They aren't necessarily "bad", just try adding some "metal safe" silicone caulk or siliconized latex caulk between the wires and the blackish ferrite to avoid any scraping/ whine as the ferrite changes size ( slightly) with each cycle of AC or of the SMPS circuit.

You could try swapping out the ATX power supply with a known quiet one in case you are unsure. Then try to isolate which unit inside the ATX.

Also, there may be nothing you can do about it. Just a design issue. Did you recently add a high current load device like a video card or a motor driver of some sort. The extra load may be pushing the power supply near or nearer to its limit which causes the whine and nothing can be done about the noise other than getting a higher max wattage power supply so you don't have to work it past 50% of max load or so.
Excellent insight on why this happens. Thanks you saved me allot of research and possibly time. If it annoys me enough Ill break open the panel and seek a better solution than gritting my teeth.

To answer your question about the high voltage device. No. I have a GPU but it has been on this box for a very long time.
 
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