Internal noise during iMac's startup. Is this normal?

[razza85]

This may be a silly question, but I need to ask it.

The main library at my uni has recently bought new iMacs; the 20inch iMacs 2008 revision. After logging on and doing what I needed to do, I logged off and restarted the computer. The computer started up with the normal "BONG!" sound and returned to the login screen as normal. Here's what bugs me. My iMac at home (2.8Ghz 24inch 2008 revision) upon powering it up makes a "ZIPZIP!" sound which sounds like something mechanical moving inside the computer, and THEN it makes the "BONG!" sound and proceeds normally. AFAIK my iMac has made this sound since I bought it back in July 2008. Why does the 24inch model make a mechanical sound at startup whereas the 20inch model does not? Oh, I should point out that my new iMac came with an upgraded hard drive from the standard 320GB to an upgraded 500GB. Maybe it's the upgraded hard drive that makes the "ZIPZIP" sound at startup?

Can anyone offer me some answers?

[NathR32]

I'm fairly sure that is just the optical drive inside. I've had that noise in most of my Macs.

[NeoRicen]

Sounds like the optical drive to me, maybe there's more noise at Uni so you can't hear it.

[xfodder]

yeah all the imacs i have used make that noise after startup, its the optical drive ... nothing to worry about.

[razza85]

Nice, thanks for your input.