Where can I download a safe Mac OS X El Capitan 10.11?

Starting up from the appropriate Recovery CD will let you erase everything that is on the Mac's drive and reinstall the original operating system.

Whether you will then be able to successfully install El Capitan or not, I don't know. You would probably need to use a modern Mac to download the El Capitan installer .DMG (or at least grab the link to its location), given that Tiger or Leopard are way too old to navigate modern https security.

Of course, if you will be giving away or selling that Mac, you could leave the El Capitan upgrade as a job for the next owner. Just warn them that they might run into problems - and be sure to give them those grey discs.

Boot from the one labeled iMac Mac OS X Install DVD.

Instructions for doing that are printed on the disc.

Is that the keyboard you have been using? If so it should work. If you are not using an Apple keyboard you might need to hold an Option key or its equivalent, which will summon a list of icons of bootable devices. The DVD-ROM (circular silver icon) will be one of them. Use the left / right arrow keys to select it then Return.

You will then use its version of Disk Utility to erase the internal hard disk drive and subsequently install that Mac's original OS X version. I can't read it from your photograph but it's probably either Tiger or Leopard. Install it and you're done. Shut down the Mac when it's finished. Do not set up a user account, and do not attempt to upgrade. That is a task for its next owner. Just shut down the Mac, and as Servant of Cats wrote provide those discs to its new owner. They will make a difference between a Mac that's nearly worthless and one that can actually be upgraded to a (slightly) more usable one.

Or you can use your OS X 10.6 Snow Leopard Upgrade DVD which you must have had at some point in order to get to later versions of macOS. Once with Snow Leopard installed, then you can upgrade the OS to El Capitan.

If you have access to another Mac generally from 2007 to 2015, then you can use it to download the El Capitan installer & create a bootable macOS 10.11 El Capitan USB installer using the instructions in the following Apple article:

Create a bootable installer for macOS - Apple Support

Here is an article which can confirm the other Mac is compatible with macOS 10.11 El Capitan:

https://eshop.macsales.com/guides/Mac_OS_X_Compatibility

The other Mac compatible with El Capitan used to create a bootable El Capitan USB installer can currently be running any version of macOS.

Another option to show that the iMac is working, would be to install Linux Mint on it. Linux Mint will provide an up to date OS with access to the most recent versions of the popular web browsers such as Firefox, Google Chrome, Vivaldi, and others. It also has LibreOffice installed by default in order to access all types of documents such as Word & Excel documents. Plus the Linux Mint software repository has access to lots of other free & open source software. Linux is a great way to extend the useful life of older computers.

FYI, the internal hard drive is the weakest link for a computer that old. I would be surprised if the hard drive is not worn out or even failing by now.

AskALotofQuestions wrote:

Immediately after you push the power button to turn it on, hold down the Option Command and the R keys. This will let you boot into Internet Recovery and reinstall the OS from there.

That Mac is too old to use Internet Recovery: Computers that can be upgraded to use OS X Internet Recovery - Apple Support

These other responses are just strange.

If there is anything strange about the other responses, it's the fact they are all 100% correct.

Servant of Cats wrote:

Starting up from the appropriate Recovery CD will let you erase everything that is on the Mac's drive and reinstall the original operating system.

Whether you will then be able to successfully install El Capitan or not, I don't know.

I thought I saw it posted on this forum some years ago that OS X 10.6 Snow Leopard was necessary to install macOS 10.11 El Capitan. Decided to check and found this:

OS X El Capitan - Technical Specifications - Apple Support

And it seems even macOS 10.7 Lion requires macOS 10.6:

OS X Lion - Technical Specifications - Apple Support

You would probably need to use a modern Mac to download the El Capitan installer .DMG (or at least grab the link to its location), given that Tiger or Leopard are way too old to navigate modern https security.

Correct. El Capitan installer must be downloaded using any other computer or OS which is able to access the Internet to download the DMG, then transfer it to the older Mac.

LightningMike wrote:

I will be selling the Mac

Don't expect to get much for one that old. That would be of interest mainly to computer collectors, someone who wanted to run really old games (if they had the games), or someone who needed a machine with a Firewire port to transfer digital video from an old (MiniDV, Digital8) camcorder onto a USB drive.

The Apple tech said it must be El Capitan, I guess that's based on my older iMac. TIA for your help.-Mike

The iMac (24-inch Mid 2007) shipped with Mac OS X 10.4.10 (Tiger), 10.5 (Leopard), or 10.5.2 (Leopard). This was in the days before the Mac App Store and before Internet Recovery, so the computer would have come with optical recovery discs that you hopefully have not lost.

OS X 10.11.6 (El Capitan) is as far as you can update it – it can't run anything higher.

That Mac shipped with OS X on optical media (DVD-ROM). Find those two discs. They must accompany the Macs they came with from cradle to grave. Period.

I would not consider buying such a Mac without those two discs, and I doubt any knowledgeable buyer would either. Even with them, it's not worth $50.

These other responses are just strange.

So you're saying you wiped the hard drive and now there’s no operating system on it for the computer to boot into when you push the power button? It gives you a black screen with something like a folder icon with a question mark when you push the power button to turn it on?

Immediately after you push the power button to turn it on, hold down the Option Command and the R keys. This will let you boot into Internet Recovery and reinstall the OS from there.

LightningMike wrote:

I'm one of those guys that usually saves everything. I have the original boxes all 3 of my Macs and just opened the 2007 box and yes! I have the two Apple CDs still in the sleeve! So what do I do next fellas?

From the links I provided in my response to @Servant of Cats, a base of OS X 10.6 Snow Leopard appears necessary to install any later version of macOS. That means you should have an OS X 10.6 Snow Leopard Upgrade DVD.

Are either of those two other Macs still working and are they compatible with macOS 10.11 El Capitan?

👍

A Mac with its original box and discs, properly prepared for its new owner as you did, will command the highest possible price. It'll be a nice find for a knowledgeable purchaser. Well done!

Makes me wonder why Apple couldn't figure it out after all the time you spent with them...

You can download from Apple How to download and install macOS - Apple Support

I cannot imagine that you would have many takers for a 17 year old, obsolete product.