My iMac High Sierra 10.13.3 fails to detect my 2nd external monitor after various attempts in settings, unplugging on/off, resetting Pram etc.
What solution does Apple offer?
iMac, iOS 10.3.3, Viewsonic VP2765-LED Display
Welcome to the Apple Support Communities!
I understand you are trying to connect a Viewsonic display to your iMac. Is this the first time you are connecting this display, or has it been connected in the past, but is no longer working? What port on your iMac are you trying to connect to? The resources below will provide some basic information for connecting and troubleshooting displays with your iMac. You may also need to refer to the owner's manual for specific instructions from Viewsonic.
Use multiple displays with your Mac
Get help with video issues on external displays connected to your Mac
Take care.
My iMac High Sierra fails to detect my 2nd external monitor after various attempts in settings, unplugging on/off, resetting Pram etc.
