I have added a second monitor to my iMac. The iMac seems to have difficulties recognising the second monitor when it comes out of power saving mode. Sometimes I have to restart the computer one or more times before the second screen starts to receive signal.
I am using a thunderbolt cable and the second monitor is a BenQ GW2760HS
Any suggestions?
iMac (27-inch, Late 2013), Mac OS X (10.7.5)
Unless your external display is Thunderbolt equipped you likely have the wrong cable. Please use a Mini-Display adapter to (VGA, HDMI, etc..) into the Thunderbolt port on the computer and then connect the correct cable to it. Then follow the Apple's directions in Use multiple displays with your Mac - Apple Support
Thanks for the quick response. What is Thunderbolt? I thought it was just a fancy name for a cable. I have tried 2 different mini display to HDMI cables, with the same result. Sometimes I can jog it into life by removing and reinserting one end or the other of the cable, and other timers a restart works, but there is nothing consistent. Do you think a mini display to VGA will fix it?
Regards
Mick
Thunderbolt is explained in http://www.apple.com/thunderbolt/.
You need an adapter cable similar to one of the ones on the following web page:
http://www.apple.com/us/search/Mini+DisplayPort+Adapter?src=globalnav
Please note that not all adapters are created alike, if you buy a cheap one then expect it to give you problems. If you buy a quality one then it should be okay. Once you have the connection made then please follow the advice letter in my initial post.
Thanks again, I bought another mini display to HDMI cable but the problem persisted. Using the links you provided, I tried the SMC reset, which I thought had fixed it but next day - same thing. Then I tried resetting NVRAM..hooray! (well-so far) If it goes OK for a few more days I will consider the problem licked. Thanks for your input.
I Will keep my fingers crossed.
Sadly the problem still exists. I can get the second monitor working by shutting down and unplugging the computer and then doing a restart. Occasionally a simple restart will fix it but once the computer has gone into power saving (sleep) mode, it ceases to recognise the second monitor until I do one or the other.
I'll try a new mini display to HDMI adapter just to fully eliminate that possibility.
Regards
Success! A new (third) mini display connector seems to have resolved the problem. I thing the best approach to this would be (1) Reset SMC (2) reset NVRAM, and if that doesn't fix it, try another connector. Happiness has descended upon my workstation.
Your welcome.
Apologies, I thought I had acknowledged you in a previous response. Thank you again for your advice which turned out to be entirely correct.
Problem with multiple displays
