Target Display Mode on the Late 2009 and 2010 iMacs was a pretty neat trick; you connected the iMac to another Mac via the Mini Display Port connector and the iMac’s display became a second monitor for the first mac while the system ran “headless” underneath it. When you unplugged the cable, the iMac’s display reverted back to the iMac itself.
The Thunderbolt port in the 2011 iMacs adds a couple of twists to this setup. First, when using Thunderbolt-equipped iMac as a display, you need to hit Command-F2 to switch the display between the iMac and the other Mac. This, however, is a relatively minor inconvenience or even a benefit, depending on how you generally use your iMac.
Another wrinkle comes in the form of what computer can connect to which iMac with which cable. To determine this we ran eight simple tests using the following:
- a 2011 iMac (Thunderbolt)
- a 2010 iMac (DisplayPort)
- a 2011 MacBook Pro (Thunderbolt)
- a 2010 MacBook Pro (DisplayPort)
- a Mini DisplayPort cable
- a Thunderbolt Cable.
We attached MacBook Pros to the iMacs in each combination with each cable. If the iMac was able to be used as a display for the MacBook Pro, it passed.
Here are the results we got:
Utilizing a Mini DisplayPort cable allows a Mini DisplayPort equipped iMac to be used as a display on either a Thunderbolt or Mini DisplayPort equipped Mac.
But when it comes to utilizing a Thunderbolt cable, only another Thunderbolt equipped Mac can use Target Display Mode with a Thunderbolt capable iMac.
No other combinations were viable.
From our testing, we see a few things.
- The only way to use a Thunderbolt-equipped iMac as a display is to hook it up to a Thunderbolt Mac via a Thunderbolt cable.
- The only iMacs that will work as a display for a DisplayPort Mac is one that also has a DisplayPort.
- DisplayPort iMacs require a DisplayPort cable, though they can work with either DisplayPort or Thunderbolt Macs.
- Only get a Thunderbolt cable if you’re going to connect two ThunderBolt-equipped computers together, it won’t work for anything else.
One final “glitch” that’s popped up seems to be relegated to a particular set of circumstances.On our 15” 2011 MacBook Pro when using a 2010 iMac as a display, we found that the video connection became unstable, as in this video.
The only solution that we’ve found at the moment is to hook the MacBook Pro up to a DisplayPort-equipped monitor (not an iMac) and let the video go through its connection there. Once it was reset, we were able to disconnect the MacBook Pro and reconnect it to the iMac.
What have your experiences with connecting display via Thunderbolt been? Let us know in the comments below.
Hello! I have a 13″ Macbook pro from 2011 (with TB) connected via a miniDP-cable to my Imac 2009. I also experience severe flickering when I connect the two and run the Imac in target-display-mode (as in the video).
However, if I keep it connected the flickering eventually stops. The time for this varies from minutes to over an hour. The intensity of the flickering also varies from time to time.
Just wanted to let you know this so you know you CAN use the target-mode. It’s really an awesome feature!
A couple of questions about possible combinations:
I would like to use two iMacs as daisy chained thunderbolt displays for my macbook pro early 2011 (6750M AMD Radeon HD 1024 MB)
Macbook Pro 2011 => iMac 2011 => iMac 2011
-Or-
Macbook Pro 2011 => iMac 2011 => Display Port Cinema Display
Currently I can only get the following behavior:
When trying to use 2 imacs as external displays for my MBP I can only set one of them to target display mode. I cannot set target display mode again to get my MBP to be the master.
When trying to use a cinema display I connect it to the iMac and see that the iMac registers it as a secondary display. When I use target disk mode it makes my MBP the master, the iMac becomes the slave, and the cinema display shows the desktop of the iMac. My understanding was that a display port display in the tail position of the chain should work.
Could you please offer some suggestions?
Apparently a current generation 21.5″ iMac and a Current generation MBA, connected via Thunderbolt cable will not display the MBA screen on the iMac. Apple is insisting that only 27″ iMac’s will work.
Just to clarify — since I have a setup similar to the one here — you CAN use a iMac with Displayport as the target in Target Display Mode while hooked up to a Thunderbolt MacBook Pro? I’ve got a Displayport iMac and it’d be nice to use it as an external display for my new, Thunderbolt-equipped MacBook Air. Thanks!
Yes, you can set that up. You will want to use a DisplayPort cable to connect the two.
So as your example above with macbook pro 15 2011 connected to imac 2010 displayport in target display mode will this glitch always happen? What if i dont have another displayport monitor so using imac 2010 in target display mode is completely useless because of glitch? Is there a fix besides the one you provided? Thanks.
By the very nature of it being a glitch, it doesn’t happen every time the two machines are used together. The plugging into another display has been the only correction we’ve found so far. We had high hopes with the recently released MacBook Pro EFI Firmware Update 2.2 that resolved many issues with Apple Thunderbolt Display compatibility, but sadly this one remained.
I have the same glitch with my Imac 27 and my new Thunderbolt enabled MacBookPro. I reported this error to Apple Support weeks ago but still no solution has been presented
I was deciding between (refurbed) 2011 21.5″ and 2010 27″ iMacs, and the irreplaceable HD on the 2011 model is getting me to lean towards the 2010 model again.
I’m currently running a 2002 MDD G4 (surprisingly sprightly for something that’s about 200 yrs old in computer years…), with a Radeon 9700 Pro (flashed PC card) as my primary video output – With the right cable (DVI to DisplayPort), I could use the 2010 iMac as a monitor, right? Whether the 9700 Pro can output 2560 x 1440 is another story…
You should have no issues running either iMac as a display, although I think you’ll find the speed improvements on the iMac may sway you to run it most of the time as your main machine. :-)
Since the 27″ iMac has another ThunderBolt port, can you try attaching a 27″ Cinema Display as well?
Apple has some serious problems with external display support on the 2011 Macbook Pro, at least the ones with the Radeon graphics. I couldn’t get clamshell mode to work at all in 10.6.7 with the graphics update, and while it works, sort of, in 10.6.6 and 10.6.8, there are lots of glitches with switching in and out of sleep or between single and dual display mode, and the occasional big crash associated with sleep. I’d also like if Apple would enable integrated graphics support on the Radeon MBPs with external display, and also with Boot Camp on built-in or external display. It’s crazy to make the computer run the Radeon chip all the time on an external display, and even crazier to make it run all the time on the Radeon even in portable mode when in Boot Camp, when the integrated solution is perfectly capable of handling it.
I understand the problems are known to Apple and being worked on, but right now I’d have to say, test before you buy if at all possible when it comes to the 15 and 17 inch laptops. I suspect the Radeon Mobility drivers need a lot more work.
Just curious. There is a big thread in the Apple discussion boards about a flickering problem when hooking up a thunderbolt Macbook Pro with the old 24 inch Apple Cinema display. I’m experiencing this too with my 2011 Macbook Pro and 24 inch ACD. I wonder if this somehow connected/related with the flickering problem your iMacs because the way they flicker looks exactly the same.
That’s interesting to know. Ironically, hooking the 2011 up to a Cinema Display is what temporarily “resolves” it for us. If you could let me know what the URL for the discussion is, I’ll certainly forward this info on to the tech who’s experiencing this problem.
Ah here you go, its a pretty huge thread and quite a mouthful to read:
https://discussions.apple.com/message/15537311#15537311
This goes against what apples documentation says…I have the new 27inch imac and the Macbook pro 5,3 without thunderbolt. Are you saying that i cant use my imac as an external display by connecting the displayport on the MBP to the thunderbolt port on the imac?
These were the results we got when we tested the iMacs and MacBook Pros listed above. When we hooked a 2010 MacBook Pro (one with a DisplayPort interface) to a 2011 iMac (with Thunderbolt), with a DisplayPort cable, we were unable to use the iMac as a display for the MacBook Pro. The results were the same with a Thunderbolt cable.
Whether this is or is not contrary to documentation, we’re not going to comment on at this time. Have you tried this sort of setup with your machines yet? What’s your experience been?
I have not tried it yet…i was about to go down and buy a cable today and just happened to see this article which discouraged me from doing that. Guess i’ll grab the cable and report back!
I have a HP docking station(for the HP Elite serie notebooks) which I use for my current assignment, which has a displayport, and connected via a displayport==>minidisplayport cable to my 2010 27″ imac(with a mini displayport input). This allowed the 2560×1440 resolution to be utilised, using the imac as an external monitor, Fantastic!! I have recently purchased a 2011 imac(with 2 thunderbolt ports), which I assumed could also function as an external display, but unfortunately this does not work. Disappointing!! I wonder if anyone knows whether this should be possible, i.e. from a displayport(HP docking station) to a thunderbolt port to continue using the imac as an external monitor?