PC hums when switched off.

Hemps

Hemps

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My HTPC get's powered down from Windows 7 whenever we have finished using it.
I noticed last night that there was a slight humming sound coming from the PC after it was switched off.

Opened case:

Motherboard light is on so power is getting to that, I'm thinking it's the power supply.

Also some power supplies come with a kill switch at the back to kill power completely and others don't, this one does, I flick that and the sound goes away.

Does it really matter or can I save power by flicking the kill switch after I'm finished using the pc?
Should I replace this power supply?
 
Yes, it's the power supply. I would use it till it doesn't work anymore and just keep on switching it off at the back. If it is still under warranty, take it back maybe?
 
Nope, it's pretty old.
Just don't want to blow anything on my PC with a dodgy power supply.

Should I replace it with a power supply with:
Kill switch on the back
OR
No kill switch on it.
 
The "kill switch" is only a plus, I would like one on my psu, but that is for a different reason...

Best is to get new one, if you can...
 
Do you actually shut down the PC or leave it to go into S3 state ? Either way I would replace it just in case. (kill switch can come in handy)
 
Brand, model?

It's probably just the active PFC. If you have noisy power lines the PFC makes that noise because some of the components are oscillating at some mains frequencies in the audible range. Power in SA isn't the best but we also get plenty of cheap components here.

For example I noticed that some cheapo florescent power saver lights we bought made the PSU make funny noises when you turn them on. Well turns out those lights spew noise all over the spectrum right into mains. Problem is some shady company imports them and no one ever reports them to SABS.
 
Try-turning-it-off-AND-LEAVE-IT-LIKE-THAT.jpg
 
You just have a cheap PSU, its not failing. Remember, their is always a 5V 1A part of ATX PSUs that is on when it has power, so that is where your motherboard gets the power from. The humming is just due to low quality design+components. I would get a decent PSU in any event.
 
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