Installing Mac OS old iMac

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Level 1

4 points

Installing Mac OS old iMac

I have an iMac from mid 2011, I tried to bring it up to the latest Mac OS version that it could handle, and it has become painfully slow, so I am trying to bring it back to an earlier version that it could handle better.

I have the original restore DVD disks, it will read them but it won't run the install package.

I tried downloading the El Capitan installer, same thing, it downloads, installed the installer, but it won't run it.

How can I wife the hard drive clean and start fresh with the original version that came with this computer.

iMac 21.5″, macOS 10.13

Posted on Oct 18, 2022 11:59 AM

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Answer 1

Best reply

Mr-Styx

Level 2

155 points

Oct 18, 2022 6:26 PM in response to Lokito

Hi Johnb-one

I wanted to add some other options for you. Your definitely on the right track as you will need to erase the hard drive to reinstall an older version of macOS.

BUT - before you do this I would recommend creating a bootable drive. The link provided below has more information.

How to create a bootable installer for macOS - Apple Support

You should also check out this Apple resource : last section: Other macOS installation options

How to reinstall macOS - Apple Support

and this link for previous versions of macOS

How to download macOS - Apple Support

make sure to read through all resources before making any steps, and if you have questions please reach out to Apple Support directly as they will be able to help out in a more hands on way!

I hope you find this helpful and best of luck!

sincerely,

-styx

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Answer 2

Johnb-one

Level 6

9,168 points

Oct 19, 2022 2:59 AM in response to Lokito

Hi, Lokito… and good morning… in answers to some of your questions : 2) 8 gigs is for older versions of the Mac OS eg Sierra/high sierra/maybe El Capitan, 16 gigs would be for later versions… anyways, the price difference between ‘em shouldn’t be much so go for 16 gigs.., as for the SSD, macsales sells a kit with a 2 TB SSD and various tools for 329 USD… ( macsales.com>SSD)) as for 7) yes, the original dvd(s) is/are bootable… 8) see link : What to do before you sell, give away, or trade in your Mac - Apple Support (CA)

that should do it from me

john b

[Edited by Moderator]

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Answer 3

Lokito Author

Level 1

4 points

Oct 18, 2022 2:52 PM in response to Johnb-one

Thank you for the response, exactly what I needed.

I did backed up all my photos into an external hard drive, this computer is ready to be erased.
I do have an 8 gig flash drive, I need to find out how to make a bootable disk out of it, the only reason I didn't try that is because at the apple help site they state 14 gig minimal, but now that you said 8, I need to figure out how to create the bootable disk.
Not sure what liondiskmaker is, will do a search, any help creating the boot disk will be appreciated.
I never setup time machine, so there is no data stored there.
Giving the cost of new machines, and how much I love the huge screen on this iMac, I think it is worth upgrading it and keeping for as long as I can, so I would be willing to make those two upgrades. I am pretty handy with my hands, not afraid of opening things up, although I have no clue how to open up this device, I taught you would have to peel the screen and that is the only way in, not sure, will have to research that to upgrade the memory and the hard drive if I can get it everything done with $300 total. I would do it myself if I can find a little of guidance via email hint hint.
Now, with errasing everything, it did cross my mind, that as long as this computer was running a newer OS it would refuse to run the original DVD, but maybe if the hard drive was wiped out, then it would have no choice but to run its original DVD, but there are some hidden steps there that I want to make certain.
Once I go into disk utility and reformat this hard drive, if I reboot the machine, turned it off / on, is the DVD bootable, is going to pick it up from the DVD when it boot back up again ? CMD+R is definitely not working. I don't want to end up with a paper weight that I can't boot up and reinstall the OS.
Even if I go ahead and post this machine for sale, I would really like not only to wipe the hard drive clean, but to scramble it well before installing a fresh copy of the OS.
I find it surreal that the machine won't even react to its own factory DVD, if anything that should be one way to bring the machine back to its beginning status.

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Answer 4

Old Toad

Level 10

208,355 points

Oct 18, 2022 1:07 PM in response to Lokito

You're already the the latest system your Mac can run. If you're having problems download and run Etrecheck. Copy and paste the results into your reply. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Additional Text button to paste the report in your reply.

Then we can evaluate the report to see if we can determine the cause of the problem.

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Answer 5

Johnb-one

Level 6

9,168 points

Oct 18, 2022 12:47 PM in response to Lokito

Fair Enough, Lokito... As you have found out, you cannot easily downgrade MacOS. It can be done, sure, but you basically have to backup the stuff on your Mac, then wipe/erase the hard drive, reinstall an earlier version of Mac OS, then using either Migration Assistant or Time Machine, get the stuff back onto your Mac, if that makes any sense to you.... so, you'd need an external hard drive of some kind, with at least the same capacity/storage as your 2011 iMac, and you'd need to connect it up to your iMac, turn on Time Machine, get it setup and working and do a backup of your iMac. Once it has done that, then you can wipe/erase your hard drive using Disk Utility.... starting from scratch... then, from there, you could use either the restore DVD's (put them into the DVD drive, label side up) or if you had it handy, a bootable USB stick (with the MacOS on it) . for that you'd need a copy of the MacOS installer (in .dmg format) plus a blank USB stick with at least 8 Gigs capacity or greater and LionDiskMaker. that's what worked for me, anyways.... I noticed that you have 8 Gigs of RAM, which is the bare minimum to run MacOS. IF you wanted to spend a bit of money, you could increase the RAM to 32 Gigs Max, which should help some.... Also, replacing the internal hard drive with an SSD would help as well... however, I don't know if you want to spend any money on it or not. I just checked OWC's website (macsales.com) and 32 gigs of ram would cost you $100. It's pretty easy to upgrade the ram, almost any person can do it, and it might require just a phillips screwdriver. As for replacing the built in hard drive with an SSD, that's possible, and it would make quite a difference in your iMac's performance, but that costs money, and as for you doing it yourself, we can't discuss that here...you'd have to seek out that information yourself

good luck

John b

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Answer 6

BobHarris

Level 9

53,693 points

Oct 18, 2022 6:16 PM in response to Lokito

NOTE: EtreCheck can be used for free. You can post the output here without paying anything. Yes, there are extra features that you can pay for, but the volunteers in this forum do not need you to pay for any of them, we just want the report which helps us because we cannot see into your machine.

The EtreCheck report does not post anything personal about your Mac, except the software you have installed that runs things in the background (often a cause of performance or other negative side-effects).

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