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Mini displayport issue on late 2009 imac

I have a late 2009 27" imac. The hard drive died so I replaced it with a SSD and installed MacOS High Sierra. Everything works perfectly.


I have been trying to use the old imac as an extended display for a newer imac (late 2013) using the thunderbolt port on the newer mac connected with an apple thunderbolt cable to the mini Displayport of the older imac in target display mode.


Neither mac can find the other as an extended display. When I run a system report of the older imac I can see the usb and firewire ports listed under hardware but not the mini displayport.


Do I need a driver for the mini displayport? should I try a MDP cable instead of thunderbolt? If anyone has any suggestions I'f be grateful for your assistance.

Posted on Mar 17, 2020 10:31 PM

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Question marked as Top-ranking reply

Posted on Mar 18, 2020 9:24 AM

The Display port won't show up in System Report, but check Graphics/Displays there... I don't have a 2nd monitor to see what might show there.


Looks like maybe the cable...


If 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.

If the primary Mac has a Thunderbolt port, it can play audio and video on the iMac. If the primary Mac has a Mini DisplayPort, it may be able to play its audio.

To see if it can, go to the primary Mac, choose Apple menu > About This Mac, click System Report, then select Audio in the Hardware category. A list of your computer’s audio devices appears. If HDMI Output or HDMI/DisplayPort Output is listed, your computer’s Mini DisplayPort can send audio. Make sure you use a Mini DisplayPort cable that carries both audio and video.

Connect the Mini DisplayPort cable to the ports on each Mac.

Make sure both computers are turned on and awake.

Press Command-F2 on the keyboard of the external display iMac.

If you want the iMac to play audio as well as video from the primary Mac, choose Apple menu > System Preferences, click Sound, then click Output.

Select the iMac in the list of devices.

1 reply
Question marked as Top-ranking reply

Mar 18, 2020 9:24 AM in response to CR1997

The Display port won't show up in System Report, but check Graphics/Displays there... I don't have a 2nd monitor to see what might show there.


Looks like maybe the cable...


If 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.

If the primary Mac has a Thunderbolt port, it can play audio and video on the iMac. If the primary Mac has a Mini DisplayPort, it may be able to play its audio.

To see if it can, go to the primary Mac, choose Apple menu > About This Mac, click System Report, then select Audio in the Hardware category. A list of your computer’s audio devices appears. If HDMI Output or HDMI/DisplayPort Output is listed, your computer’s Mini DisplayPort can send audio. Make sure you use a Mini DisplayPort cable that carries both audio and video.

Connect the Mini DisplayPort cable to the ports on each Mac.

Make sure both computers are turned on and awake.

Press Command-F2 on the keyboard of the external display iMac.

If you want the iMac to play audio as well as video from the primary Mac, choose Apple menu > System Preferences, click Sound, then click Output.

Select the iMac in the list of devices.

Mini displayport issue on late 2009 imac

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