psu switched off but speakers still make noises

[sighwinder]

why do my speakers make crackling noises from time to time although my psu is switched off? they are usb charged. i don't have any issues with other peripherals. the led on the back of my speakers also goes off, but when the crackle noises happen it switches on for like half a second. this happens with two different pairs of speakers and different usb ports. my psu is always cold, the 12v, 5v, 3.3v rails voltages are perfect and constant. what could be the problem? does the psu store some electricity and the speakers are extra-sensitive? is this normal? of course, if i unplug my pc completely the noises disappear. thank you. my psu is a Sirtec - High Power Element BRONZE II 600W.

 

[mbarnes86]

Hi

If you mean you shut down the PC from windows then the psu is still capable of providing power

What about sleep mode?
Or wake on lan ?

Usb led mice usually glow while the PC is off.

One you switch off at socket or unplug the mains then the capacitors eventually discharge,
however there are often safety warnings not to open psu case as there are high voltage on psu capacitors remaining for some time after un plugging the mains cable from wall socket.

Regards
Mike barnes

 

[sighwinder]

no, i turn the pc from windows AND i switch the psu off from the back of the pc. that't why it's weird.

 

[sighwinder]

i also discharged the psu this afternoon, unplugged it and held the power button on, to be sure ab that. no difference

 

[mbarnes86]

Hi

If the speakers are usb charged do you mean they have built in batteries?
If so

Radio frequency interference picked up by connections to the speakers may be causing the noise

Try with speaker connection cables disconnected from rear of your PC but still connected to speakers and see what happens

Regards
Mike Barnes

 

[sighwinder]

no batteries. these are the speakers. http://www.amazon.co.uk/Acme-SS-204-2-1-Speaker-System/dp/B006PSGYLK/ref=cm_cr_pr_product_top/279-1133729-5088415

 

[mbarnes86]

Hi

The only other thought I have is mains bourne interference from near by power cable when some thing is switched on or off causes the noise

Regards
Mike Barnes

 

[sighwinder]

but do you think my 'problem' can be something serious like a faulty psu or mobo? otherwise doesn't really bother me as i don't switch my psu off that often anyway.

 

[mbarnes86]

Hi

You don't seem to have any symptoms of problems so I would not worry

Regards
Mike Barnes

 

[sighwinder]

thank you for the answers.