Still have Imac noise issue

Hi,
Im still struggling with a low pitched noise from my Imac. Its a low pitched drone that oscillates in volume high and low over about a 3 second cycle. I have my Mac in a quiet room now and its driving me crazy. Not what I expected with my first venture into Apple and buying the top of the range Imac available. Ive been to the Apple store but they cant here it properly with all the noise and are pretty unhelpful actually.Been there twice now with Imac in tow.
Has anyone else had this problem?
The store says its the hard drive and its normal. Surely not.
Ive read on the forum that it may be the screen which is what I think it sounds like.
Is there a way to put the screen to sleep and leave the hard drive active or put the drive to sleep and leave the screen active so that I might be able to tell when the noise disappears?
Another clue is that when the screen dims the noise gets louder slightly.

Appreciate your help if you can. Its really spoiling my Mac experience.

Mike

Is there a way to put the screen to sleep and leave the hard drive active or put the drive to sleep and leave the screen active so that I might be able to tell when the noise disappears?

Click to expand...

Open System Preferences, Energy Saver. Remove check from the box that says "put hard disk to sleep..." and then set a very short time to put the display to sleep.

Also, it would be helpful when you post if you would include the specs of your Mac. That way, if someone else with the same machine and same problem has a solution they can post it back to you.

Regards.

I noticed a "heartbeat" noise from my 27" iMac right after I bought it. I called the store and they suggested I bring it in. They really couldn't hear it but they gave me a new machine...no questions asked.;D The new Mac does the same thing so I'm not going to worry about it...