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My old iMac EMC 2389 failed (and I forgot the password for my time capsule). I have removed the WD Caviar Blue HD, attached a SATA to USB3 cable and plugged it into a USB3 socket on new iMac 21.5" but the computer will not read it . Would booting up with the Option key held down get it to read the old HD? If not, how do I retrieve the data please?
3.5" drives need additional power than what the USB port can offer. So if you’re not using a powered unit like what IFIXIT sells [linked product missing or disabled: IF107-108-1] it likely isn’t getting enough power. The other factor here is if you enabled drive encryption then you won’t get anywhere without the backup key. Lastly, your drive could just be gone. As you didn’t explain what happened with your old iMac this still could be your problem. OK, lets say you are able to get your drive to be seen. I assume you want to transfer the user accounts, apps & your data over to the new system. This is were you want to use Migration Assistant app. Using it allows you to re-gain access to your TimeMachine backup as the transferred user account will have your saved passwords.
Just plugging in the hard drive with a data to USB 3 cable will not do the trick as the hard drive needs power as well data. You are better off getting an inexpensive SATA caddy . These come with power and can read 2.5 and 3.5 " hard drives. Then once attached to your new iMac you can mount it on the desktop and copy your data off. You can , like you mentioned , hold down the option key to see if your new iMac can see the old drive as a bootable device . The only time this may not work if the hard drive has failed in which case, as long as you can mount it ( may not be likely if HD has failed) you can run some recovery tools on it. Hope that helps
