30

The Ins and Outs of Your iMac's Target Display Mode

Posted by Jim Tanous on January 4, 2014
Target Display Mode iMac Xbox 360

A benefit of Apple’s iMac is that users get a monitor and computer in one relatively small package. But unlike a standalone monitor, users were traditionally unable to share the display with another computer or device, leaving the iMac’s large and high quality screen dedicated only to the Mac within.
Apple sought to address this shortcoming in 2009 with the release of a new feature called “Target Display Mode.” Available initially only on the 27-inch Late 2009 iMac, Target Display Mode (TDM) allowed users to plug a compatible device into their iMac’s Mini DisplayPort and gain exclusive use of the iMac’s display. With the proper adapters, DisplayPort can accept DVI and HDMI sources, meaning that practically any computer or video device using these standards could work with TDM, including PCs, game consoles, and even other Macs.
Target Display Mode quickly became a much-loved feature of the 27-inch 2009 iMac, and it persisted with the 27-inch 2010 model. With the introduction of Thunderbolt on the 2011 iMacs, however, things suddenly became far more complicated.
Prior to Thunderbolt, the iMac’s Mini DisplayPort connection was used exclusively for video and audio. Thunderbolt changed all of that by bringing data I/O into the mix. Now, users could not only add displays to their Mac, they could also daisy chain all manner of hard drives, storage arrays, card readers, and other external devices. Even though Thunderbolt also handled DisplayPort video, the new complexities of the Thunderbolt controller meant that Target Display Mode would be far more restrictive.
With Thunderbolt-capable iMacs – the Mid 2011 models and up – Target Display Mode will only work with other Thunderbolt-capable devices. This means that connecting another Thunderbolt Mac to your iMac, such as a 2012 MacBook Air, will work just fine, but devices that only output HDMI or DVI, such as the Xbox One, won’t work.
This limitation disappointed many users. While it’s great to still be able to use TDM with newer Macs, most who took advantage of the feature connected non-Apple devices such as gaming PCs or consoles, especially in small workspaces where having a second display for these other devices was impractical or undesired. All things considered, we wouldn’t trade the benefits of Thunderbolt for the return of broader support for TDM, but those hoping to use the feature should be aware of its limitations.
That said, here’s a simple breakdown of the various iMac models that support TDM, and the limitations for each. For the chart, “Source Output” refers to the device that you want to connect to the iMac’s display, and “Connection Cable” is the cable type required to make the connection between the two devices.

ModelSource OutputConnection Cable
Late 2009 27-inchMini DisplayPort or ThunderboltMini DisplayPort
Mid 2010 27-inchMini DisplayPort or ThunderboltMini DisplayPort
Mid 2011 21.5-inchThunderboltThunderbolt
Mid 2011 27-inchThunderboltThunderbolt
Late 2012 21.5-inchThunderboltThunderbolt
Late 2012 27-inchThunderboltThunderbolt
Late 2013 21.5-inchThunderboltThunderbolt
Late 2013 27-inchThunderboltThunderbolt

As you can see, because Thunderbolt outputs DisplayPort video, you can use a new Thunderbolt-equipped Mac to connect to the display of an older iMac via a Mini DisplayPort cable, but not the other way around. For any iMac after the 2011-era, it’s Thunderbolt all the way.

How to Use Target Display Mode

If your hardware meets the requirements above, and your host iMac is running OS X 10.6.1 or higher, here’s how to use Target Display Mode.

  1. Both the iMac and the source computer or device will need to be booted up and awake. Once they’re ready, use the appropriate Mini DisplayPort or Thunderbolt cable to make the connection between the two.
  2. Using the host iMac’s keyboard, press Command-F2 to trigger Target Display Mode. You’ll see the iMac’s screen go black for a second or two, and then switch over to acting as the display for the source computer or device. Note that even though the iMac’s display is now in use by the source device, the iMac itself will continue to hum along in the background. Any running tasks or apps will continue without interruption, and you can even remotely log into the iMac from another computer to use it while the display is busy.
  3. When you’re ready to switch control of the display back to the iMac, simply press Command-F2 again. Alternatively, you can shut down the source device or disconnect the display cable; if the iMac in TDM stops receiving an active video signal from a source device for any reason, it automatically switches the display back to default.

Target Display Mode Tips & Caveats

As long as your hardware meets your expectations, TDM can be a great feature, but there are some tips and caveats you’ll need to be aware of.

  1. Target Display Mode won’t give you a “free” Apple Thunderbolt Display. What we mean by this is that when you connect a computer to your iMac, don’t expect to gain any hub functions like those found the Cinema and Thunderbolt Displays. Your source Mac won’t be able to see or use the card readers, USB ports, iSight cameras, or microphones of the host iMac. It’s only video and audio, folks.
  2. You can use more than one TDM Mac with a single source device. Target Display Mode basically turns your iMac into simple monitor, so if you have two iMacs and, let’s say, a new Mac Pro, you can put both iMacs into TDM, connect them to the Mac Pro, and have two displays for your new Mac workstation. Note, however, that you’ll need to connect each display directly and individually to the source; you can’t daisy chain iMacs in Target Display Mode.
  3. While in Target Display Mode, you should be able to change the brightness of the iMac’s display or the volume of the speakers using the iMac’s keyboard. However, some users have reported difficulty with these functions since the introduction of Thunderbolt in Snow Leopard. If you have difficulty controlling the brightness in Target Display Mode, check out third party solutions like the app Shades, which offers fine-tuned brightness controls for any Mac, not just those in TDM.
  4. Some users report difficulty simply getting their iMacs into Target Display Mode. Be sure to check the integrity of your Mini DisplayPort or Thunderbolt cables, and make sure that the actual ports on each device are working. If you’re connecting a third-party device, such as a game console, via an HDMI to Mini DisplayPort adapter, also be sure to independently verify that the adapter is functioning properly. If all else fails (and we wish we didn’t have to say this), some users on Apple’s support forums report success with repeated presses of the Command-F2 keyboard combination. We’ve never encountered that issue on our end but, hey, it’s worth a shot.
  5. You don’t need to worry about your host iMac sleeping and breaking the connection. While in Target Display Mode, the host iMac automatically ignores any scheduled sleep commands and keeps the system running as long as the source’s video signal is flowing. If your source device sleeps, however, it will break the connection and the host iMac will revert to the internal display.
  6. While 2011 model iMacs and up are practically limited to serving as external monitors for other Macs (due to the Thunderbolt source requirement), those using 2009 and 2010 iMacs with devices other than computers should note that there are some input resolution restrictions. By default, the iMacs can only accept DisplayPort input at 720p or native resolution (which, in the case of the 27-inch iMac, is 2560-by–1440). This means that if you attach an Xbox console, for example, via one of the HDMI to Mini DisplayPort adapters you’ll get your console’s output at 720p, and it will then scale to fill the screen, producing a full-sized but less sharp image. However, there are some more expensive products that have built-in scalers and can take a device’s 720p or 1080p output and scale all the way up to 2560-by–1440.

Apple’s Target Display Mode is certainly not as flexible as many users might like, especially after the Thunderbolt transition, but it’s still a great feature that ensures that your iMac’s big beautiful display won’t be entirely locked down to the components inside. So if you need a display for your MacBook in a pinch, or you’re hoping to repurpose an old iMac as a second monitor for your new Mac, Target Display Mode is the way to go.

30 thoughts on “The Ins and Outs of Your iMac's Target Display Mode”

tabby1921 says:
why can’t a 21.5″ mid 2010 Mac be used in target display mod? Can it be upgraded to do so?
Reply
TGL says:
Hi I have an late ’09 iMac, tried to connect Mini DP to HDMI adapter to the iMAC then HDMI cable to TV or PS4. That did not work. Do you know what the issue is? And what adapters I need to make this work? I would like to play ps4 on the iMac Monitor. Thx
Reply
Morton says:
Is it possible to connect a Mac Mini 2014 with a Thunderbolt v2 connection into an iMac from 2011 which uses Thunderbolt v1?
Reply
Morton says:
I have the setup now and can confirm that YES, here in 2019, Target Display Mode (TDM) works from between a MackBook Air Thunderbolt 1 interface (10Gbps) is flawless with no lag when transmitting its screen contents to an iMac from mid-2011.

It works slick and smooth and I highly recommend it!

Reply
FKM says:
I would like to ask if it is possible to connect a pc (Dell 7577 thunderbolt 3) to my Imac 2011 (thunderbolt) with the adapter “Thunderbolt 3 (USB-C) to Thunderbolt 2”, and use the Imac as a second or external screen?
Can anyone help me?
Tanks.
Reply
Mark says:
I have the exact same question. I have an HP Zbook with Thunderbolt 3 and used an apple thunderbolt cable and thunderbolt 2 to 3 adapter and can’t get it to work. My HP sees the Apple device but my 27” mid 2011 iMac never enters TDM. Any help would be appreciated since I purposely ordered this PC because of its thunderbolt 3 integration.
Reply
Mark says:
Hi FKM & Mark, were you able to resolve this? I have a late 2013 iMac and an HP laptop with thunderbolt 3 so was hoping the same (‘Thunderbolt 3 cable’ to ‘Thunderbolt 3 to Thunderbolt 2 Adapter’) would work.
Thank you.
Ross Young says:
Also, the two computers have the following specs and software:
MacBook Pro (Retina 15″ Mid 2014) running OS X Yosemite Ver. 10.10.5
iMac (21.5″ ,mid 2014), running the same software version as above.
Thanks
Ross
Reply
Ross Young says:
Hi
I’m connecting an iMac and a Macbook Pro with a Thunderbolt cable and following instructions for TDM. It works!! I can get the Macbook Pro to display on the iMac by using Command/F2, but, incidentally, only by closing the lid of the Macbook Pro. This is all fine, except that with the lid closed I can’t use the keyboard of the MacBook Pro, AND I just can’t find a way to get the iMac’s bluetooth keyboard to work in that configuration. Does anyone have any solutions to allow me to use the keyboard? Thanks, Ross
Reply
Chandu says:
Hi
can i use non Apple keyboard ( a general USB keyboard) for TDM using command + F2.. I have tried using it, it dint worked out. but it only works with Apple keyboard. Can anyone help me out …
Reply
toknowjoyman says:
Sorry to bump up a really old post, but I’m having an issue with TDM that needs some expert (not genius) input.
I have a late 2011 iMac (with mini display port) and 2012 macbook pro (w/thunderbolt).
I actually have 5 sets of these . But they dont seem to be working with TDM, ive tried with mini-display and thunderbolt cables with no luck. Any suggestions ?
Reply
jack says:
Hi. ? re using new mac mini with old imac screen
I want to get updated apple software especially safari but also keep my old software ( particularly iphoto ) and disc drive on my 2011 iMac -it has a thunderbolt socket . I wondered whether if I get a new Mac mini I can link this to ( ? via target display mode) and use the old 2011 iMac just as a display without any effect on the old mac software etc -this would also save space rather than buying a new ? laptop or iMac. If this is possible would I still need to plug the keyboard and mouse to the mini or get a separate mouse /keyboard for this?
Reply
James says:
Can you combine an 2017 iMac 27 inch 5K being the source with an 2013 iMac 27 inch (still 2K I believe) being the target display, for Target Display Mode? Knowing the 2017 iMac had Thunderbolt 3 (USB C) and the 2013 iMac has Thunderbolt 2?
Reply
Bombart says:
I have that setup and confirm that it does work. You’ll need a Thunderbolt 3 -> Thunderbolt 2 adapter and a Thunderbolt 2 cable.
Reply
Travis H says:
TekRevue, I know this is an older post, but what is that product in the photo at the base of the iMac in the photo, sitting in front of the keyboard?
Reply
TekRevue says:
That’s the HiRise for iMac stand from the company Twelve South. It’s basically just a metal stand that’s designed to raise the height of the iMac, either for ergonomic purposes or to make it the exact same height as the Apple Thunderbolt Display (for those who use it as a second monitor).
Reply
Noé Sardet says:
Hello TekRevue. I connect my 2013 Macbook pro retina to my 2011 iMac, with a thunderbolt cable, press Command F2, and nothing happens. It works with a 2013 Macbook though and I checked specs of the Imac, it should work according to the model. Is there a possible incompatibility with retina Macbook Pros?
Reply
Lance T. Osborne says:
Hi Noé. Were you able to get this resolved? Looking into doing the same thing with my 2014 rMBP -> 2011 iMac.
Reply
Noé Sardet says:
No, I was never able to use my Imac as a screen although the configuration and specs should work… Any advice on how to solve this?
Lance T. Osborne says:
Haven’t tried it yet – my cable is on the way. One thing I learned is that you must use Thunderbolt cable from Apple – generic cables and ones from Dell, etc. won’t work. Is yours a genuine Apple cable?
I’ll try later this week after I get the cable and check back in…
Lance T. Osborne says:
Hey Noe – Checking in. Got the cable, and it dreams like a dream. Make sure you’re pressing Cmd + F2 on the *iMac*, not the Macbook. Good luck!
Noé Sardet says:
I will try it again. Thanks
Tyler Pena says:
Does this work with a MacBook running windows 10 with boot camp to an iMac? Trying to boot camp my 2011 MacBook and use my iMac plus another monitor as displays while running windows 10.
Reply
TekRevue says:
It should work with a source device (your MacBook) running Windows, because the iMac doesn’t care about what’s on the input signal, only that it’s the correct type. As for running two displays, it seems that MacBooks from 2011 can only support a single external display up to 2560×1600. What model year is your iMac?
Reply
Tyler Pena says:
It’s a 2015 iMac 5k so I guess it wouldn’t be full res but good enough. Trying to decide whether to boot camp the iMac and have to switch back and forth between OS or just boot camp the MacBook and use iMac as secondary display
TekRevue says:
Just make sure you use a Thunderbolt cable to connect the Macs, but you’ll only be able to use the iMac alone without another display.
Depending on what you need Windows for, you could also run a Windows virtual machine using VirtualBox (free) or one of the commercial alternatives (Fusion/Parallels).
Allen says:
I have tried to connect my late 2009 27 inch iMac as a monitor for a new 27 inch Retina iMac without success. I have checked that the late 2009 iMac is actually late 2009 and I have gone through all of the steps detailed on the web. I have connected the two computers using a Thunderbolt cable between the Thunderbolt port of the Retina iMac and the Mini Display Port on the older iMac. The result is that the target iMac does no react at all. Have you any ideas as to how I can find out why the TDM is not working.
Reply
林志恒 says:
Can I connect iMac(Mid 2011 21.5-inch) to my MacBookPro(Mid 2014 13-inch) by mini displayport to mini displayport cable?
Reply
TekRevue says:
You can connect them, but you must use a Thunderbolt cable. It looks like a mini DisplayPort cable except for the lightning bolt icon on the connectors. It will not work with a standard mini DisplayPort cable.
Reply
Tabe de Vries says:
Hi, I’m trying to connect my Xbox One to a mid-2010 27″ iMac using an HDMI to Mini Display Port. It won’t even let me enter TDM at all after pressing cmd + F2 multiple times. Is there something I’m doing wrong??
Reply
TekRevue says:
No, the iMac must receive a Thunderbolt input signal. All that adapter does is convert the Alienware’s HDMI output to DisplayPort. Mini DisplayPort and Thunderbolt 1/2 share the same port size, but are not the same technologies. There’s unfortunately no method currently available to consumers to take simple HDMI or DisplayPort and convert it into a Thunderbolt input. So you’re stuck with Thunderbolt-only sources (i.e., Macs and some PCs) for input on the 2011 and newer iMacs.
Reply
Iven Blomberg says:
Is it possible to send video form ex. GTX10 series card via thunderbolt? What additional hardware would you need? i have a 2011 iMac and want to build a PC for casual gaming, if i could use the iMac as monitor it would save me some money and deskspace. I have googled this topic and have not been able to find any examples of gaming type pcs using a imac as a display.
Reply
Lauren Piekarski says:
Hello. I connect my Macbook pro retina to my iMac, with a thunderbolt cable, press Command F2, and nothing happens. I’ve tried putting it in Target Disk mode etc etc, but I don’t understand what the problem is. The one time it worked, it mirrored my laptop screen, but thats not what I needed…. I wanted a needed second screen. I would very much appreciate advice and input! Thank you
Reply
Br. Bill says:
Mirror mode is the default. You need to change the mirror setting in Display preferences.
Reply
ikkemittvalg says:
I want to use a late 2009 27 inch as dual monitor on my late 2012 27 inach imac .. am i correct that i can use a mini displayport to minidisplayport cable for this ? or must it be a mini display to thunderbolt ?
Reply
Jonah Wei-Haas says:
I have tested connecting my 2011 MBP to my 2009 iMac via mini displayport cable and successfully worked in TDM on iMac.
My question is, will the TDM work on my imac if I connect using a mini displayport to HDMI cable, which would plug into the hdmi port on a thunderbolt hub. So the thunderbolt hub is connected to my MBP, and then using the hdmi port, connect that into the minidp port on my imac. Will TDM still work on iMac????
Looking forward to your response
Reply
Gus Sanderson says:
Another user had a similar question, but the GTX 10 series comes with a DisplayPort on the actual GPU. It doesn’t have a Thunderbolt port, but can I plug in a DisplayPort to Mini-DisplayPort cable into the iMac and GPU, and have it function in TDM?
Edit: I have a 2012 27-inch.
Reply
Klunkolini says:
Hi! The GeForce 1080 has display ports. Would Displayport (from the 1080) to my (mid 2011) 27″ iMac work? I’ve spent a lot of time researching this and some say that it works if you use a minidisplay to minidisplay cable.
Reply
Gus Sanderson says:
I’d really like to know this as well.
Reply
TekRevue says:
Sorry, this answer is late; I missed your question when it was posted.
The answer is no, all 2011 and newer iMacs require a Thunderbolt source to work with TDM. Mini DisplayPort and Thunderbolt generations 1 and 2 use the same port size, but are completely different technologies. You would need a GPU or PC with a Thunderbolt output to work with your iMac. I don’t know of any discrete consumer GPUs which have Thunderbolt outputs, but there are a few PC motherboards which have Thunderbolt ports.
Absent a source device with Thunderbolt support, there’s no adapter or trick or any other method which will make this work.
Reply
Eric Wi says:
Guess I’m lucky to be using a 2010 iMac then 😀
Reply
Carmelo Iaria says:
Anybody being able to use the iMac TDM with Microsoft Continuum?
Reply
TekRevue says:
If your phone or Continuum dock supported HDMI output, you could use a 2009 or 2010 iMac in Target Display Mode, as it will accept an HDMI video input signal. But it won’t work with 2011 and newer iMacs, because they require a Thunderbolt connection, and Continuum doesn’t output Thunderbolt to displays.
Reply
Carmelo Iaria says:
does it have to be a Thunderbolt cable?
I’m trying
MacBook Air mid 2011 -> Thunderbolt-2-HDMI Adapter -> HDMI Cable -> HDMI-2-Thunderbolt Adapter -> iMac mid 2011
and TDM won’t work …
is this expected?
Reply
TekRevue says:
Yes, it must be a Thunderbolt cable.
Reply
ishyg says:
What if the iMac is dead? For example, it won’t go past the Apple screen during boot. Is it possible to TDM at that point?
Reply
TekRevue says:
It depends on what is broken. Target Display Mode initiates at the firmware level, so it doesn’t necessarily require that the target Mac’s hard drive or OS are working properly. If the motherboard and graphics card are still functioning, it should still work.
Reply
ishyg says:
I’ll try to make it work. Thanks.
Anteo Zlatic says:
Hi, I want to connect my ps4 with my iMac (Late 2012 21.5-inch) to play on it. Is that possible?
Reply
TekRevue says:
No, you can only connect HDMI-based devices like the PS4 to 2009 and 2010 iMacs. For Macs newer than that, your source device must output Thunderbolt, which limits you to Macs and certain PCs only.
Reply
Anteo Zlatic says:
If I buy a hdmi adapter for my Imac, would it then go?
TekRevue says:
You could buy an HDMI video capture card, but those are meant to record gameplay when your console is hooked up to a TV and have a slight lag, so it wouldn’t be very good for playing games live. There’s no way to natively connect any HDMI device to your 2012 iMac.
Venna says:
hi, I connect my thunderbolt cable to Macbook Air (11-inch, mid 2012) with iMac (21.5 inch, Late 2013). When I press Command F2 in my iMac keyboard it works great. However, I would like my macbook air to be the additional monitor not my imac. So i tried to press Command F2 in my macbook air keyboard but it doesn’t work. Any ideas how? Thank you
Reply
TekRevue says:
Hi Venna,
Unfortunately, Target Display Mode doesn’t work that way. Target Display Mode is only available on certain iMac models, which means that only the iMac can be used as the second display.
Reply
MeGaPk says:
If i connect by HDMI-> Mini diplay port cable to iMac 2009, i can give 2k resolution, if on my pc, videcard support it?
Reply
xeondxb says:
I know this thread is old but im giving a try maybe some help anyway.i have 2011 mid IMAC 27inch and macbookpro 2013 late retina im trying to connect with thunderbolt cable after connecting both together on my imac and macbook pro thunderbolt port shows inactive but when i connect macbook air 2012 with my imac,it immediately become active and also i can see macbook air display on imac …
Reply

Leave a Reply to xeondxb Cancel reply

Your email address will not be published. Required fields are marked *


Disclaimer: Some pages on this site may include an affiliate link. This does not effect our editorial in any way.