Small buzzing sound coming from back of M…

Small buzzing sound coming from back of Mac Pro - Is this normal?

Hi there,

I've noticed there's a buzzing sound coming from my brand new 2010 Mac Pro if I listen closely from the back. It sounds like an electrical buzz and even though it's only audible from the back of the machine, I'm a little concerned this might get worse and worse over time. I don't remember hearing the same buzzing on my 2005 Power Mac G5. I'm not 100%, but it might be coming from the power supply. Has anyone else experienced this? It's only audible when you listen closely from the back.

If someone could go behind their Mac Pro and listen for a buzzing sound that would be great so I will know whether it's normal or not. Don't get me wrong. The buzzing sound is not annoying in any way as I cannot hear it from where I sit. I'm just concerned that it might lead to something worse or even damage my Mac Pro over time.

Thanks for reading and I hope to hear from somebody soon.

Regards,

Daniel

Mac Pro 3.2GHz Quad-Core Intel Xeon "Nehalem" (Mid 2010), Mac OS X (10.6.4), 12GB 1066MHz DDR3 SDRAM

Posted on Sep 27, 2010 10:11 PM

Nov 9, 2010 5:00 PM in response to chrisuk123

I have the same issue of a buzzing PSU, however I am only getting after receiving a replacement PSU (third in fact)
My Mac Pro wasn't starting (at all) after pressing power button, it would get power for a second and then turn off (before chiming)
I had the power supply replaced first and machine booted for 2 days (without a buzz) and then refused to turn on again. I had the front power button board, logic board and some sensors replaced and after getting it back working, it would refuse to power up after 1 or 2 days.
So after quite a long ordeal, they decided to replace the PSU a second time (the first replacement logic board they received from apple was DOA (dead on arrival) so they thought that maybe the PSU had the same issue as the one it first replaced.
Wouldn't you know, the second PSU replacement fixed the problem (working for almost a week now)
However, upon first power up and on every subsequent power up, I get a rather load PSU electrical buzz as described by others on here.
On all occasions the buzz disappears after about 5-10mins and doesn't reappear until the machine has been turned off and back on or sometimes after returning from sleep.

So the good news here would be that the buzz ISN'T normal as I never had an issue until I received a replacement PSU and in some cases it doesn't last forever (i'm not sure if others have had it disappear after a while or if it stays)

Something to note, when you get parts 'REPLACED' from apple, on most cases, the part you get is not necessarily a NEW part, but rather, a refurbished part from a previous repair. This is usually always the case when an iPod/iPhone is replaced and why sometimes when you get a replacement that you can encounter other, completely different issues with the replacement.