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Use external monitors with your Mac

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Question: Since upgrading to High Sierra, I can no longer use a second monitor to work with my Mac?

What do I need to do to use two monitors with my mac now that I've upgraded to High Sierra?

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Answer:

Start with an SMC reset and an NVRAM reset

<Reset the System Management Controller (SMC) on your Mac - Apple Support>

<How to reset NVRAM on your Mac - Apple Support>

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May 31, 2018 9:51 AM in response to dienel In response to dienel

I have this same problem (iMac 27" late 2013, OS 10.13.4), and am unable to use a second display via Thunderbolt intermittently--sometimes it works, sometimes it doesn't. I have restarted multiple times/ways, reset SMC and NVRAM multiple times, trashed preferences, changed cables and swapped Thunderbolt ports, nothing will consistently solve the issue.

May 31, 2018 9:51 AM

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Question: Since upgrading to High Sierra, I can no longer use a second monitor to work with my Mac?