New 20" imac humming?

Hi I'm a new member here and new to Macs so bear with me.

I got my imac a couple of weeks ago and everything has been great apart from one thing.I'm getting a humming from the unit which is like the sound of the harddrive spinning in the unit being transferred into the table that it is sitting on.When I tilt the base of the unit back or forward so it is not sitting flush on the table the humming stops! I presumed it was just the particular table that I had the imac on that may be sensitive to sound vibrations or something,but its the same in different locations.In fact as I'm typing I have a book under the base of the unit to reduce the humming noise.

Now its not hugely loud but it is annoying all the same.Is this normal or should I consider returning the unit?


Thanks in advance for any help.

Could it be a resonance running through the foot of the machine? I don't have an iMac but assume the foot isn't attached when you receive one. Does the seating need adjustment?

Martin@martinsk said:

Could it be a resonance running through the foot of the machine? I don't have an iMac but assume the foot isn't attached when you receive one. Does the seating need adjustment?

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It is a resonace running through the base.The foot is already attached from out of the box and cant be adjusted as far as I can see.