Using a 27-inch iMac as an external display for my macbook air

(Oops accidental post)

Did you figure out what the problem was? Was your cable defective? I can't get mine to work either. I'm using the Belkin MiniDisplay Port to Mini Displayport from a 13" MacBook (non-Pro but from the period when the MB looked just like the MBP) to a 27" iMac (late 2009).

From what I have read you need to use a thunderbolt cable - although these look the same as the mini display cables they are different. I know for definite you can connect a new thunderbolt macbook air to a thunderbolt enabled iMac or 27" display and I am *told* that you can also connect the air to an older iMac's mini display port, again using a thunderbolt cable.

Doesn't appear to be the supported TB-->MiniDP. See http://arstechnica.com/apple/news/2011/09/apples-thunderbolt-display-doesnt-play -nice-with-mini-displayport.ars . Some options listed.

Though there seems to be a contradiction here: http://docs.info.apple.com/article.html?path=Thunderbolt/10.6/en/30822.html where it is stated f you have a 27-inch iMac with a Mini DisplayPort, any other Mac with a Mini DisplayPort or Thunderbolt port can use it as a display. Make sure you have a Mini DisplayPort to Mini DisplayPort cable.

Morning seal, my experience suggests the latter of your two posts is the correct one. I have a 27" iMac with a mini display port (a 2-year old one, not the newer one with thunderbolt); and a brand new Mac book air with thunderbolt. I connected the two with a Belkin male-male mini display port to mini display port cable, and it works fine - press command f2, and the iMac acts as display for the MBA.

The irony here is that the folks at the apple store in Paris assured me that this would NOT work, and that I needed to buy a €999 thunderbolt display to connect to my MBA. I thought I'd try anyway, since I had the cable to connect a MacBook pro to the iMac anyway... Glad I did.

Bottom line: yes, despite all the confusion, the new MacBook air will connect to the minidisplay port of an older iMac 27"; and the cable it needs to do that is the older minidisplay port cable, not the thunderbolt one.

Here's how it seems to me:

If you have a new (mid-2011) iMac, it will only function as an external display if the source (say a mac laptop) is Thunderbolt equipped (i.e. new). If you try to plug an older laptop into a new iMac, while the mDP to mDP cable will fit into the Thunderbolt port on the iMac, it will not work because the source is not Thunderbolt.

On the converse, however, an older iMac can be used as an external display either by a newer laptop (with a Tbolt output) or an older laptop (with an mDP output).

Good info. I bought an iMac w/ the goal of upgrading w/ a mini or laptop after a few years. Thanks.

Hi all, Hi OS Paris... I have a question (maybe a little OT, sorry).

I have a old IMac 2006 with Mini-DVI output port with support for DVI; can I use this IMac like an external display for a new MacBook Air, perhaps via a "Mini DisplayPort to DVI Adapter" cable?

Thank you in advance for the replies...

Hi Rossella

As far as I know, only the recent (from late 2009) iMac 27" can be used as an external display. On other Macs, I believe the DVI port is only "out". But I could be wrong on this -- any more knowledgeable folks, feel free to correct me!

There is another thread where you can find some help here: https://discussions.apple.com/thread/1188860?start=0&tstart=0

All the best

Rosella,

The following is true for iMacs starting in 2009. Not sure about 2006.

If you have a new (mid-2011) iMac, it will only function as an external display if the source (say a mac laptop) is Thunderbolt equipped (i.e. new). If you try to plug an older laptop into a new iMac, while the mDP to mDP cable will fit into the Thunderbolt port on the iMac, it will not work because the source is not Thunderbolt.

On the converse, however, an older iMac (2009-10) can be used as an external display either by a newer laptop (with a Tbolt output) or an older laptop (with an mDP output).