later drives have an extra connector, which means if the correct apple drive is not fitted, the mac won't boot. i think it might be from 2011.

earlier ones are ok to change, just flipping awkward.

In reply to a post by cookie:

later drives have an extra connector, which means if the correct apple drive is not fitted, the mac won't boot.

As far as I can discover- rubbish.

They'll boot OK, but because the OS can't sense the drive temperature it ramps the fan up to full speed (~6,000rpm) to be on the safe side. Which is irritating.

The app that The Horseman mentioned earlier is probably the best way around the problem, though there are others.

See this article for example (scroll down to Hard drive upgrade issues)

If you have a link to somewhere it says that it won't boot, I'd like to see it?

Edited by billford (Thu 28-Mar-13 10:36:09)

you are correct, i am mistaken in the non booting issue.

Either a Seagate or a WD will be fine. I have three iMacs and had drives replaced under warranty and then done it myself after AppleCare expired. The trickiest part is getting the glass off the 27" model then replacing it.

There are several videos out there showing how to do it.

QUOTE.
"The HDD in one of my iMacs is dying... the number of re-allocated sectors is growing at a depressing (though not yet alarming) rate ".
END QUOTE

Can you tell a mere novice how to find out about re-allocated sectors?
My G4 iMac has started to make buzzing noises which seem to come from HDD and I would like to monitor the degradation progress.

Or should I just get it replaced as a precaution?
Is there a reliable competent repairer roughly in South Manchester area who would do this job?
[Please don't tell me to buy a new Mac - my better half has just got herself a new MacBookPro.]

The G4 iMac was bought new in Apr 2002 from John Lewis. Thanks to the 2-year JL Warranty a noisy HDD was replaced free in 2004. It has been fine till last few days.

Inconvenient as we are just getting Fibre connection by zen/BT - the last thing I need is a crashed HDD.

In reply to a post by DIOGENES:

Can you tell a mere novice how to find out about re-allocated sectors?
My G4 iMac has started to make buzzing noises which seem to come from HDD and I would like to monitor the degradation progress.

Or should I just get it replaced as a precaution?

I used this- Smart Utility. It's free for a month, which should be long enough to either set your mind at rest or confirm your worst fears

Is there a reliable competent repairer roughly in South Manchester area who would do this job?

Can't help with that- I'm nowhere near that area.

From Apple's website...

Manchester, Manchester Arndale
New Cannon Street Mall
Manchester, M4 3AJ
016 1455 1900

Manchester, Trafford Centre
146 Peel Avenue
Manchester, M17 8BL
0161 240 1000

I would steer well clear of the 7200.12 drives. They have inherent problems which Seagate seem to be completely ignoring. there is no firmware fix as there was with 7200.11's.