Mac Pro Makes A High Sound When Its Off! Please Help...

hi everyone!

so here goes…my mac pro is old (2007) and works quite fine, but i noticed a couple of times when it was off and i was in the room that something started to buzz (like high electricity sound or when you are near a big power tower or something similar…its a really high sound and not so loud, but very annoying).i found out that it was mac…but it was off! so i turned it on and everything seems to be fine. this happened 2 times in this week, so I'm worried!

please help…thank you!

N

Is it powered off, or just sleeping? I would first suspect that you have a failing capacitor in the power supply. It still supplies power, even when the system is turned off.
Does the buzzy sound go off when you unplug the power cord on your Mac Pro?

I don't think there's too much to worry about, although the sound is likely very annoying.
The power supply may eventually stop working, or might cause other problems in the event of erratic power.

One work-around would be to unplug your MacPro after you turn it off.

The fix would be replacing the power supply. Or, repairing the power supply - which would mean troubleshooting to discover which part, or parts, are bad.

thanks for a quick reply

yes it was completly off and not in sleep mode. i will try to unplug the power cord next time.

but is this problem maybe related to another annoing thing that it does-when i put it in sleep mode the display wont wake up.the computer wakes up and all that i press works, but the display is just sleeping (it shows power saving mode on the screen for a few sec when i press the button). i dont know what else to do in that situation so i press power off button and restart it. what else could i do when that happens? now i rather shut it down than put it in sleeping mode because of that... :/

thanks a lot! *

If you continue as you are doing now (occasionally forcing the power off), you also run the risk of corrupting your system, or your own files.

When you sleep your MacPro, the display would also go to sleep (the power saving mode). When you wake the MacPro, then MacPro sends a wake signal, while also turns on the graphics card. I suspect that the power supply is not working well enough to do that reliably
If your display has its own power switch, can you try turning that power switch off, then back on? That MIGHT cause it to come back on, without the challenges of forcing your MacPro power off.
However, if the display is not coming on, because it doesn't get a working video signal unless you actually restart your MacPro, then that is likely additional info telling you that your power supply is simply failing.
A tip to try - reseat your graphics card in its slot. That will clean up minor corrosion on the card's connector, and can sometimes help your graphics card to function better, particularly if yours has not moved since 2007.

But, your main issue is _probably_ the buzzy noise that you hear. If it is the power supply, then it likely means that you have a capacitor or several capacitors close to failure. easiest fix is replacing the power supply. I can give you Apple's part number if you want to search for a part. I need to know exactly which MacPro you have - two different MacPro models, with different power supplies, were sold at the same time during 2007

my mac is MacPro 2,1 if that helps..if not, tell me what info do you need…thanks a bunch

and i hope this doesn't cost too much cause i am currently poor

Apple's part number for the power supply for a Macpro2,1 is 661-4309.
Here's an example of a price: http://www.usedmac.com/products/661-4309-power-supply-980w-for-mac-pro-8x-new
I looked at other sites, and around $150 appears to be a pretty good price, but you can also check on eBay.
You can look at the iFixit repair guide for that - https://www.ifixit.com/Guide/Mac+Pro+First+Generation+Power+Supply+Unit+Replacement/32222
You'll likely pay much more for labor than the part itself if you have someone else do it.

Or, you may have a noise that will continue without real effect for months, or years - and you can likely work around that by unplugging power after you turn your MacPro off.

well..for now i will just keep unplugging it and when some money comes... but thank u for all the info!

have a nice day

N