Can I revive my dead iMac?

July 22, 2013 8:51 AM

I have an iMac that appears to be dead. Can I use an external HD to revive it?

My iMac (27", Intel, circa 2008) appears to have a dead hard drive. It was frozen this morning, and then on a restart, I get nothing but the white screen with the flashing file folder containing a question mark. A little research showed me that it's probably the HD, so that means replacing the HD or the entire machine. A new machine isn't feasible, and I can't really afford to screw up replacing the HD, which looks pretty involved for an iMac, so as far as replacing the HD, it's probably Genius Bar time for me.

Then, as I was thinking about other options, I had a thought that may or may not work. I have a 1TB external HD attached to the iMac that currently has about 250G of data on it. Can I install OS X on this HD and somehow boot the iMac to it, instead of to its internal drive? If that would work, how would I go about getting the iMac to boot to the external HD?

(As a side note, all my data is backed up to the cloud, so I'm not at all worried about data loss from the dead HD; I'm set as far as that goes)

posted by pdb to Computers & Internet (12 answers total)

I think you'll need to boot from a CD first, install on the external HD and then boot from the external HD. Here are a list of the keystrokes you'll need to ensure the machine boots from the intended volume. I've done this a few times with different Macs (not yours, though--but I don't see why it wouldn't work).
posted by Admiral Haddock at 8:59 AM on July 22, 2013 [1 favorite]

If you want to keep those 250Gb of data then copy them off the HDD first. I'm not certain but I think that installing OSX for the first time on a drive means it's going to get erased.

Then plug it in and boot from CD as Adm. Haddock says.

You will be offered the chance to install to any HDD that the Mac can 'talk' to. Install OSX as specified on the external HDD. When the installation is finished and the CD ejects, the machine should boot to the new volume and that ought to be that.
posted by jet_silver at 9:07 AM on July 22, 2013

If you want to keep those 250Gb of data then copy them off the HDD first. I'm not certain but I think that installing OSX for the first time on a drive means it's going to get erased.

No, that's not true.
posted by Blazecock Pileon at 9:30 AM on July 22, 2013

You *might* need to erase the external disk if it is presently formatted as FAT or NTFS. It's been a while since I installed Mac OS X on an external drive, but there may be a requirement that a Mac boot disk be HFS.

I'd back it up beforehand just to be safe.
posted by chazlarson at 9:36 AM on July 22, 2013

The flashing file folder means that the iMac cannot find a System file to boot from. It does not necessarily mean the HD is borked. If you have the Mac OS System DVD simply boot with the DVD in the drive and holding the C key. Then open disk utilities ( DO NOT Reinstall the OS yet) and run tests. Then if necessary reinstall the OS with the option to save the data.
posted by Gungho at 9:36 AM on July 22, 2013 [1 favorite]

Response by poster: Thanks all - Haddock and Gungho's comments lead me to a followup question. I have an OS X Lion CD, but I upgraded to Mountain Lion via the Mac App Store a few months ago, so I don't have a CD for that.

Can/should I use the Lion CD to get up and running again, and can I then somehow re-install Mountain Lion without paying for it again (I still have the order ID/documentation), or is there a way to burn a bootable copy of Mountain Lion (yep, probably should have done this at the time, of purchase, but here we are) since I have purchased it?
posted by pdb at 9:47 AM on July 22, 2013

Install Lion, then open the App Store application and enter your Apple ID. You can reinstall ML from there, along with any other apps you've bought.
posted by Blazecock Pileon at 9:53 AM on July 22, 2013 [1 favorite]

Best answer: When you installed Lion and later ML Apple created a recovery partition on your drive. Try booting while holding Command-r (Apple-r). This is the same as booting from a Mountain Lion DVD. If it doesn't work you can boot from the Lion disc and reinstall ML from the App store.
posted by Gungho at 1:05 PM on July 22, 2013

Booting from the lion DVD will let you run disk utility as mentioned, it does not need to be the newer version. In dist utility run the "repair disk" and "repair permissions" options then reboot. I'd also try this routine, and this before proceeding any further. Then try this. After that though if it passes the disk test portion, since your stuff is backed up i'd just format the drive and reinstall lion.

This [?] bootup screen is like a smoke alarm. It can mean there's a fire, but lots of other irritating situations can set it off as well when there is in fact no fire, just a bit of smoke. Sometimes stuff just gets inexplicably corrupted. It's happened to me several times over the years with intel macs...
posted by emptythought at 2:14 PM on July 22, 2013

For your original question: Yes, you can boot and install OSX just hunky dory with external volumes. They'll need to be formatted with HFS+ though. You might also want to look into if your machine was recalled. My 27" iMac with 1T drive was recalled for a drive replacement.
posted by chairface at 5:41 PM on July 22, 2013 [2 favorites]

Oh i forgot about the recall! check that before you bother with anything else. This might just be a "trip to the apple store, free repair in an hour or overnight" gig here where they install OSX again for you and everything.

Ignore the fact that the page says "The program covers affected iMacs for three years after the first retail sale of the unit or until April 12, 2013". This is the kind of rule they pretty much always bend, especially when you're just a couple months outside that bracket.

I also forgot to recommend in my previous post against using an external drive as a boot volume. It'll make your system feel like it's from 1994 but trying to run modern software. Like, truly load times measured in tens of minutes molasses speed stuff.
posted by emptythought at 5:49 PM on July 22, 2013

Response by poster: So, a week later and I finally had time to sit down and work on this. Gungho's tip was all I needed; running a few tests and booting from the recovery partition had me back up and running again in less than an hour.

Thanks all for your help.
posted by pdb at 1:34 PM on July 29, 2013