Strange Electrical Buzzing Noise From Power Supply Unit

[Jaisudha]

Hello..........

Hey guys Please help me out with my situation. I was using my Pc last night when i noticed an electrical buzzing noise from my PSU. I want to add to it that I only plugg in the power cord from the outlet and switching the power button on the PSU. I have tried numerous PSU and different outlet within the house with the same result an annoying buzzing noise which I am pretty sure is coming from the transformer. An electrician has also checked the circuitry and all is in working order. Is this buzzing noise coming from my PSUl? I would appreciate any suggestions or personal experience that may resolve this problem.

[Rawko]

I am not an Electrical Engineer but check this Points:

• Passive PFC inductors in some power supplies. This buzzing sound is generated by low frequency viberation of magnetized cores of the Passive PFC inductor and has a low frequency.
  
• The switching stage circuit of the PSU. Because the switching frequency is usually above 50KHz in design, this noise is usually beyond hearing limits of human kind (20Hz~20kHz). However if a lower frequency viberation is generated in the feedback loop, you may hear it from the viberation of coils, tenuous but sharp sound.
  
• DC-DC VRMs are used on both Mobos and Video cards. Usually the viberation of inductors (or capacitors) can't be heard because of the ultra-high frequency(>100kHz I think), but if there's lower frequency resonance (<20kHz) for some reason, the lower frequency components can be heard.
  
• If there's no load on one of the PSU's output (12V, 5V, 3.3V, 5Vsb), the PSU is working abnormally and can emmit buzzing sound. Enhance uses a 20Ohm resistor as the load on 5Vsb output and calls it "standby noise filter". Clever design.

[deoWo]

hi there......

Sounds like a bad fan, or problem in Fan blade .It's possible for you to just replace it. They start up at full speed and within a minute or so they usually settle into temperature controlled mode and start making buzzing noise.

[RoninBlade]

Try this one:

PSUs are one of the most overlooked components of a PC. Do yourself and for your motherboard a favor and buy a quality PSU - it will save your motherboard and stop much headache in the future or else a lot of money will cause in buying your other components due to voltage fluctuations, burning out, etc. and if you're having stability problems it'll help those too.

[Fabian]

i believe in simple and quick solution..........
just either replace fan or your PSU.......

this really helps........
short and simple solution..........