changing iMac hard drive

[Pyx Findlekind]

>Date: Fri, 14 Mar 2003 07:04:40 -0800
>Subject: [HM] Re: changing iMac hard drive
>From: T. Brown / groucho <btgroucho at earthlink.net>
>Message-Id: <47C0C718-562E-11D7-9489-003065703A02 at earthlink.net>
>
>
>On Friday, March 14, 2003, at 06:08  AM, Pyx Findlekind wrote:
>>
>>  Is this 7200 RPM installed in an iMac?
>
>It's in a 333 iMac. The drive is a Maxtor 30 gig BTW.
>
>>  Is there an issue with overheating?
>
>No problems at all. It's been in there since 2000.
>
>>   Is there an increase in the noise level?
>
>No the opposite, a dramatic decrease in sound levels. There is
>however that droning fan still.
>
>groucho

Question: Which generates the most heat - HD or CPU?
Also: I'm noticing an increase in HD noise level recently when the 
iMac is inactive (hum/buzz). Is this something to be concerned about? 
Am I just imagining this?