4mot/4/40000002: hdd-0

Do you have the Snow Leopard 10.6 Install Disc that came with your 2011 iMac computer...?

If you do, then follow the instructions below.

1. Boot from your install DVD 1, click on Utilities and open Disk Utility.

2. Highlight the new HD in the list of drives and select the Partition tab.

3. Under Volume Scheme select 1 Partition and click on the Options... button.

4. Select GUID Partition Table in the drop down window and click OK.

5. Set the Format to Mac OS Extended (Journaled) and click the Apply button.

6. Once thats done then you can do a clean 10.6, them update to 10.6.8.

If Disk Utility can not see the 2T Seagate in step #2...? Then it is either bad or not properly installed and you need to start over with a different Hard Drive.

Your HDD has failed.

You will need to have the HDD replaced and then restore from your backup.

Look like "the fan for the hard drive" acting up -- as the notorious issues from 2009 - 2011 iMac models when replacing the had drive.

Did you have in line thermal sensor installed as well??

Sam, I think that you are spot on there!

After some more research, I also concluded that it is a fam motor error and not an HDD error. It would have made things a lot easier, if to OP would have initially given better details. 😉

To wistuk:

If you replaced the HDD and it is working properly, but the HDD fan is running at full speed...?

Then you need a special hard drive cable with a built-in thermal sensor.

see > OWC In-line Digital Thermal Sensor for iMac 2011 Hard Drive Upgrade