upgrade imac 7,1

You can install Linux Mint onto the iMac assuming the internal hard drive is still healthy. It is a non-Apple OS so it will require you to learn a new OS. Linux is not for everyone, but it is a great way to extend the useful life of older computers since it gives you a current non-Apple OS which supports the current versions of many popular web browsers (Firefox, Google Chrome, Vivaldi, and others), plus you have access to LibreOffice and lots of other free open source software within the Linux Mint software repository.

Linux works best with at least 4GB of memory, but can be used with as little as 2GB if only a single app is open and only a couple browser windows/tabs are open at one time. You can even test drive Linux Mint by choosing the "Live" option when booting the Linux Mint USB installer. Keep in mind Linux will run extremely slow when booted from the USB stick, but will run great when installed on the internal drive assuming it is still healthy.

You may even be able to check the health of the hard drive when booted into the "Live" mode of Linux Mint....check to see if the app GSmartControl is on one of the menus (may be located on the "System" menu of some Linux distribution)....feel free to post the complete GSmartControl health report here and I will review it. This hard drive health report can give us a good idea if the hard drive is still healthy. Sometimes another Linux app may be installed which has the same ability. A bootable Knoppix USB stick definitely has GSmartControl installed by default so that can be used to check the health of the iMac's hard drive.

Edit: GSmartControl may be on the "System Tools" menu instead. I am not currently at my Linux system to check.

Niel wrote:

Back up your data, check the application compatibility table, Install Mac OS X 10.6 from a DVD, update to 10.6.8, click here, and then on the download link for El Capitan.

That would normally be good advice, but I'm afraid that the Safari Web browser in Snow Leopard is so old that it can't handle modern https:// security. Including the https:// security on the How to download and install macOS page to which you linked. Catch-22!

The .DMG links within that page do not use https, so I think that Snow Leopard's version of Safari should be able to handle them. For the OP's benefit, the El Capitan link is El Capitan 10.11 .

Back up your data, check the application compatibility table, Install Mac OS X 10.6 from a DVD, update to 10.6.8, click here, and then on the download link for El Capitan.

rkaufmann87: An iMac7,1 is a 2007 model.

(248529)

Your iMac is at least 14-15 years old and is extremely obsolete. Please let us know the model year of the iMac (click the Apple symbol in the upper left of the display and then click About this Mac) and that information will be revealed. Once we know the model year we can tell you the latest version that your iMac will run.

Seriously though, you should upgrade to a new Mac though.

Once you're on El Capitan, you might want to install Firefox 78 ESR. This is many, many versions behind the current one (121.0). It is so old that it no longer gets security updates from Mozilla. Still, it might allow you to access a few Web sites that the version of Safari in El Capitan has problems accessing.

https://support.mozilla.org/en-US/kb/firefox-mac-osx-users-esr

Firefox isn't the only application where being unable to upgrade past El Capitan is going to leave you stuck with an outdated version – or locked out entirely. El Capitan is eight major versions behind Sonoma, the current version of macOS. So it's not supported by Microsoft or Adobe. Even a lot of other developers are now requiring versions of macOS that are higher than Catalina.