Buzz from PSU when pc is off?

Sweeney · 27 Dec 2008 at 23:45

Just fitted a new BeQuiet! 1200w PSU (yes overkill and a half, i know, t'was a christmas present so why not

).

Like the idea of it continuing to spin fans when system is shutdown to disperse heat etc but once the fan stopped i couldn't help but notice a very faint buzzing noise. Switched the psu off and it stopped, started again when i switched it back on of course.

Should i be concerned? I remember reading about (Zalman i think) having a switch on the inside end of their PSU to reduce/stop "standby noise", so im assuming its normal and just my sensitive ears managing to pick it up?

TheStig1983 · 27 Dec 2008 at 23:50

not sure m8 but mine don`t make that noise,you got it as a christmas present?now why can`t i have presents like that i only got socks

again

ChrisLX200 · 27 Dec 2008 at 23:51

Lots of beefy transformers in there, bound to hum a bit on standby.

Sweeney · 28 Dec 2008 at 12:09

Its a very very faint buzz/hum ie. ear right up to it, otherwise you can't hear it. I'll give it a couple weeks see if it gets louder or anything

Corasik · 28 Dec 2008 at 13:15

Its very common, there is a little circuit called 5VSB (5 volt stand by), which typically powers USB ports, the on board clock and cmos (the battery is only a backup for the clock during complete power fail, or when unplugged), Lan cards with wake up on lan ability etc. Depending on the PSU it can by up to 2 amps of power.

5vsb is also used to power the RAM chips if you use S3 deep sleep mode, which is how some computers can boot within seconds of powerup.

Can hear my PSU's buzz from 2cm away from the back of the supply, but any farther away and its as good as silent. If you can only hear it with your head right next to the PSU then its normal. Some PSU's buzz louder, or even tick (ticking PSU's are more annoying imho).

It does seem quite often that the bigger rated PSU's have more tendancy to buzz a little when only delivering the standby power.

BTW, PSU's which switch right off (or unpluging them) will generally shorten the life of the cmos battery, as most motherboards will use 5vsb to power the cmos and clock when available.

Wayne~ · 28 Dec 2008 at 13:18

One of my old PSUs used to do it just something you grow to live with!

Sweeney · 28 Dec 2008 at 13:27

I knew part of what you just said Corasik but it makes perfect sense now, considering i need my head right at it to hear it.

Replies i was looking for chaps, cheers! Im just a bit of a worrier when i hear weird and wonderful noises