2012 imac with new external display - mirror only possible, not extended / dual mode

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2012 imac with new external display - mirror only possible, not extended / dual mode

I have connected a) my 2015 MBP and alternatively my 2012 imac 2012 fusion 3.1ghz to an external samsung diplay via Thunderbolt 3 / Mini DP - DP cable

I am able to make an extended and rearranged display with the macbook but not the imac - both are running big sur etc - internet says both should be able to have an extended display but imac gets mirroring only.

any answers guys?

PS i can get the imac to show the extended display only if i switch on PBP / PIP mode in the Samsung which is designed primarily to connect two machines to one monitor rather than 2 monitors to one machine

thanks in advance

Posted on May 26, 2021 8:24 AM

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Answer 1

danakayw

Community Specialist

May 27, 2021 9:09 AM in response to mephistocles

Hi there mephistocles,

Thanks for reaching out to Apple Support Communities. We understand you’re using a Samsung monitor with your iMac and MacBook Pro. You’re unable to extend your display using your iMac. We’ll be happy to help.

To start, let’s look over this page to go over the basics and make sure all looks OK there: Connect a display to your Mac. You can test with only your iMac and Samsung monitor connected. If you still can’t extend your display, let us know.

This page offers more details on using multiple monitors with your Mac: Use multiple displays with your Mac.

The steps at the bottom of this page can help with troubleshooting Thunderbolt 3 issues: Get help with video issues on external displays connected to your Mac. If you need further assistance, you can reach out to Apple Support using the link at the bottom of that page. We hope this helps.

Best regards.

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Answer 2

danakayw

Community Specialist

May 27, 2021 12:33 PM in response to mephistocles

Thanks for reaching back out mephistocles,

We'd like to gather some more information to see if there are some additional steps we can have you try. Did it work in the past? If so, what is different now? Let's try connecting only the iMac and Samsung, after restarting the iMac and attempting to adjust the Settings again.

Best regards.

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Answer 3

mephistocles Author

Level 1

19 points

May 27, 2021 11:54 AM in response to mephistocles

thanks for the very detailed reply - sadly the mac just wont allow itself to be in extended screen mode unless the samsung screen (4k 2 HDMI ports, one DVI port) is setup as PIP which then only uses half the screen - in order to get there in the first place you have to fiddle with both of the screens parameters : for example i click on mirror screen and nothing happens until the display prompt in Mac preferences displays 30hz refresh - as the samsung is a 50/60hz screen it only responds once you move the drop down to 60hz. Then again you can only use is as a mirror screen which is pointless for the mac.

Any other ideas would be really useful thanks.

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2012 imac with new external display - mirror only possible, not extended / dual mode

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