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Hi I’m trying to use my Mid 2011 21.5 iMac as a display for my 2013 Mac Pro the 2011 running High sierra and 2013 Running Catalina they’ve both been connected by thunderbolt and I’ve tried everything on apples support page saying how to set it up however it is simply not working and im incredibly confused as i would like to get this working for the iMac to become a second display for the mac pro
iMac 21.5″
wait, what?
The last dozen posters who complained about this not working were not following ANY of the rules, and you are following them ALL.
Use your iMac as a display with target display mode - Apple Support
so I presume you are already logged out of any user on the iMac and have pressed Command-F2
have you also tried any of these?
To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.
This query is only sent at certain times:
• at startup
• at wake from sleep — so momentarily sleeping and waking your Mac may work
• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go
• hold the Option key while you click on the (Detect Display) button that will appear in Displays preferences (from another display)
so try doing some of those things and see if the display comes alive.
Make sure that the cable that you are using is a Thunderbolt 1 or 2 cable – not a Mini DisplayPort one. While both types of cables use Mini DisplayPort connectors, the Thunderbolt cables may be built to higher standards.
what version of MacOS is running on the MacPro?
what version of macOS is running on the iMac?
The iMac is running 10.13.6 High Sierra and the Mac Pro is running 10.15.7 Catalina
Target display mode not working on 2011 iMac and 2013 Mac Pro
