iMac Noise: Please Diagnose

[Hatchet]

I purchased my iMac 2.8ghz 24" in July.

It's been running fine but just recently, it's been making this noise that comes from the back of the iMac (middle top). If I put my iMac to sleep, it goes away and I can hear it power down.

It does not sound like a fan and I checked my istat and fan speeds are the same as usual. I called Apple Support and they too said it wasn't a fan issue but they weren't 100% sure if it was the harddrive.

Could this be my hard drive making noise? Do I need to make an immediate backup to make sure my data is secure?

The problem is, it comes and goes, so if I bring it into the Genius bar, I may not be able to replicate the issue.

It doesn't sound good and I know it shouldn't be making the noise.

 

[EricNau]

Can you explain the sound? What does it sound like? Whirring, clicking, buzzing, beeping, etc.

 

[Hatchet]

Can you explain the sound? What does it sound like? Whirring, clicking, buzzing, beeping, etc.

Medium pitch Buzzing...however, i can hear it power down when I put the iMac to sleep or turn it off.

Doesn't sound like a fan because it isn't pushing air...

 

[wamund]

Same(?) problem

I also have a 2.8 GHz 24" iMac. Have this annoying chittering/buzzing mid-high pitch noise coming from the top back-side of the machine. It is appearing when putting my screen to sleep.

/Mikael

 

[Clyde099]

My 2.8/24" also has noticeable noise coming form the HD's activity.

 

[mannix87]

I'm experiencing a similar problem with my 20" iMac. it just started doing it today. I tried all available software update thinking that it might just be some software incompatibility but it didnt do the trick. neither did restarting it or shutting it down. the fan seems to be in a permanent 'on' mode. anyone here know what's wrong? the HD temp is steady at 40 degrees C

 

[mannix87]

this worked for me. I shut down the iMac and unplugged it, gave it a few seconds then plugged it in and booted it up. the fan noise disappeared. so far, it seems to be fine. i'm still wondering though as to what triggered it