iMac dual monitor setup: How to connect an external monitor to your iMac

iMac dual monitor setup FAQ: Can I connect an external monitor to my iMac? (Or, how do I use the Apple Mini DisplayPort to connect a second monitor to my iMac or MacBook Pro?)

Yes, you can connect a second monitor (external monitor) to your iMac — here's how.

iMac dual monitor - iMac Mini DisplayPort

To create a dual monitor iMac, first locate the "Mini DisplayPort" on the back of your iMac. You can see the iMac Mini DisplayPort in this photo:

iMac dual monitor setup (iMac external monitor setup)

(Image courtesy of Apple, with a few words rearranged, and the red dot above the iMac monitor Mini Display port added by me to make it more apparent.)

Using this iMac display port — and the correct cable, which you'll have to buy — you can connect your iMac to an external monitor.

iMac dual monitor setup with Mini DisplayPort

According to the iMac technical specs, the iMac Mini DisplayPort provides "output with support for DVI, dual-link DVI, and VGA video". Which iMac monitor cable you need depends on the external monitor you want to connect.

Very specifically, you can buy one of these three iMac monitor adapters at an Apple store, or other places, such as BestBuy:

  • Apple Mini DisplayPort to DVI Adapter
  • Apple Mini DisplayPort to VGA Adapter
  • Apple Mini DisplayPort to Dual-Link DVI Adapter

Again, which adapter you need to buy depends on the second monitor (external monitor) you want to connect to your iMac. (If you're not sure which iMac monitor cable you need, please see the Apple links below for more information.)

iMac dual monitor setup

Once you get the correct adapter cable for your external monitor, the iMac dual monitor setup process is simple. With your external monitor turned off, connect the monitor to your iMac with your new cable(s), and then turn your second monitor on. In a few moments your iMac will recognize the external monitor, and you'll see your Mac desktop appear on that monitor as well. After that, it just becomes a matter of how you want to use your iMac dual monitor setup.

(Until I get more time to write about this iMac dual monitor setup process, I'll just say, "See your Mac 'System Preferences' panel for more dual monitor setup information".)

iMac second monitor - Monitor adapters cables

As mentioned above, to connect your iMac to an external monitor, you'll need an iMac monitor adapter cable. You can get these from a variety of sources, but here are links to these iMac adapter cables on the Apple store website:

Most external monitors these days support DVI or VGA cables, so you'll probably want one of those first two monitor cable types. The $99 Dual-Link DVI Adapter lets you connect to an Apple Cinema display, and if you have one of those, well, hey, good for you, lol.

iMac dual monitor setup - Summary

I hope this information on how to configure an iMac external monitor (iMac dual monitor) has been helpful. I like connecting an external monitor to my iMac for a variety of reasons, including (a) keeping my RockMelt browser on that screen, (b) playing movies on that screen, and (c) using the extra monitor as a "clipboard" location, where I can place notes while working on something else, like this blog post.

As usual, if you have any questions or comments leave a note below, and I'll do what I can. In the meantime, connect an external monitor to your iMac, and see what you've been missing. :)



So, the 27" imac and the 27" cinema display both have speakers. I tried setting up the speakers by creating an aggregate device in audio-midia setup - but I have had no luck in getting the sound to come out of both displays. Any ideas?

Good question, and I wish I had an external monitor with speakers to test this with. (My external monitor doesn't have speakers.) After digging around and rewriting this response several times, here's what I've found:

  • iMac models built after mid-2010 support audio-out in the Mini DisplayPort. You can find that information on this Apple support page. (So, if your iMac was build prior to mid-2010, this DisplayPort won't support audio-out. This is more or less confirmed on this Wikipedia page.)
  • According to that same page, "For this feature, use Mini-DisplayPort to HDMI adapters that conform to the VESA v1.1a DisplayPort Interoperability Guidelines."
  • On this other Apple support page they also mention some Mini DisplayPort to HDMI adapters that should work.

I don't know if that helps much, but that's all I could find.


Thank you so much for posting this information. I really like my iMac, but was not happy about giving up my laptop and external moniter. I like lots of real estate! Now I am a happy camper and will get the Apple Mini DisplayPort to VGA Adapter ASAP.


This is my third external monitor which I've attempted to hook up to my late-2011 iMac with Thunderbolt. I came armed with photos to the Apple Store and spoke with two reps. Both assured me the Belkin Mini DisplayPort to HDMI Adapter was what I would need. The Mac does not recognize any of the monitors and am now thinking there is something about the Mac which I need to change or something? Everywhere I've looked it's supposed to be this automatic thing.

It's hard to say, but what I usually do to troubleshoot something like this is what it sounds like you've started: try multiple monitors, and try multiple cables with those monitors. I have several different Macs that I purchased over the last three years, and usually when I connect an external display it just works.

You can connect a monitor and then go to System Preferences > Displays, but I doubt that will do anything.

On one of my Macs the speaker port is dead, so I know that it’s possible to have one dead component and the rest of the system can keep running. When that happened I ran Apple’s hardware self-test. Here’s an link on how to do that.

Sorry that I’m not much help. Those are the things that come to mind.