How to Turn an Old iMac into a 2nd Monitor - Cheaply!

If you've got an old iMac laying around, here's how to turn it into a high-quality 2nd monitor.
Good monitors are expensive and if you've got an old iMac laying about for just a few bucks you can turn it into a 2nd or 3rd monitor. Using either Duet Display or Luna Display that old iMac can be brought back and put to work.

[CourseBuildersAcademy]

How to turn an old iMac into a 2nd Display - Cheaply and Quickly!

[JamieWooster-de]

imagine paying a monthly service, let a lone a fee of any kind, to use your own old computer as a second monitor. lol

[gravescreativedesign]

I was done when they said it was a subscription. No thank you.

[gutoverissimo]

The cable connection doesn't extend your old Mac's screen as a second screen to add additional workspace. This simply mirrors the screen, but does not add additional workspace.

[darrenbellenger]

That looks like a slimline iMac, I thought they were released in 2012. My 2012 iMac is slimline and my 2009 iMac is chunky - the iMac in this video does look slimline to me, so couldn't be from 2006.

[chewtony]

Thank you very much for your sharing! Thanks for all those options you suggested!

[tomascj.]

Thanks ever so much for the video, Andrew. It has helped me a lot, you have earned a subscriber ;-). I bought the Thunderbolt cable and plugged to my Mid 2015 Macbook Pro and my 27-inch late 2013 iMac (both updated on software and both connected to wireless internet, both showing orange light) However I do not get the Dual Display to work. Would you know what could be the issue? Thanks a million in advance for any tips advice how to fix it! Tomas

[tiffsterritoryonyoutube]

Orders in and fingers are crossed. Thanks for links, visuals always help.

[yasarnawab]

Hey Andrew, How to use my 2018 imac to my PC as monitor? Please show that?

[jujujustme]

Hi. I think your 'old' iMac shown is a 2016 slim-line, not a 2006. Duet does not support 10.11 El Capitan, which is the highest OS a 2007 iMac can handle. But, great info for those who have an older/newer iMac.

[sami_sert]

thunderbolt cable only works on pre-m1 chip intel supported macbooks and no extra software is needed. When you use duet, which connects only over the network with Mx chips, I cannot say that the connection is very efficient in this.

[jaychoitexas]

It doesn't seem to work with Macbook Air M1 although you uploaded the video when M1 was available.

[mr.k]

Is there a way of having an older mac as a secondary monitor AND running two different OS on both machines? Thanks!

[Eeczit]

Well, the adaptor does not work with a macbook air M2 right? 😅

[RooniFaye-zy]

When you say "connect your computers together with an ethernet cable" do you mean an ethernet (to be plugged into early 2009 iMac) to usb c (for a 2018 Mac with thunderbolt)?

[jackhopkins]

its the paddy mcguiness of the Mac world lol! quality accent lad!

[FreshAnton]

i tried the Thundebolt Cable Version (with Thunderbolt 2) on iMac from 2017 and a Macbook M1. the Thunderbolt Icon turns yellow like yours but i cant switch Tabs from one screen to another. Any Ideas?

[BrandonBurk]

I have a Macbook Pro (Retina, 15 inch, Mid 2015). I want to mirror it onto a bigger iMac screen. I own 3 iMac computers (mentioned below).

iMac (27-inch, Late 2012) 
Running macOS Catalina 10.15.7

iMac (27 inch, Mid 2011)
Running macOS High Sierra 10.13.6

iMac (24 inch, Early 2008)
Running OS X Yosemite

Question:
Am I able to screen mirror my Macbook Pro (Retina, 15 inch, Mid 2015) to any of my iMac computers.

[maximusaugustus]

I have a 5K 2015 iMac 27", with Big Sur, I wanna use it as a monitor. Anyway, could I connect to my new Notebook Pro M3?

[vooracties]

Sorry for my bad English, I’m not a native speaker.
In your video you say that the old mac can run 10.11 El Capitan with Luna.
But if I look on their website I see that 10.13 High Sierra is required on the secondary device.
I still use 10.11 on the old mac and can't upgrade (because of legacy software).