Mid 2011 iMac - external monitor sleep issue

Question

Mid 2011 iMac - external monitor sleep issue

I have a new mid 2011 iMac (max configuration), and I'm experiencing an odd issue with one of my monitors at all times (I have two external 27" panels connected).

I have my iMac connected to two ASUS VE278Q full HD monitors via DVI using two Mini Display Port to DVI adapters. The issue is always with the third monitor in the OSX display list (identified is Display 3). It does not matter which order the monitors and Mini Display Port to DVI adapters are connected to the thunderbolt ports, or what DVI cables I use; the issue persists.

The issue is that when the displays all go to sleep, the 3rd monitor goes to sleep correctly, but it then awakens from sleep after only 1 to 2 seconds. It then goes back to sleep, and then wakes again. It does this cycle indefinately. I have seen other users on the support forums with thunderbolt Mac Book Pro's having the same issue with external monitors, so I hope a future software or firmware update can resolve the issue.

Apple has replaced one of my Mini Display Port to DVI adapters in order to see if the adapter was the issue, but it did not solve the issue. In fact, the new adapter has a different issue it causes (display corruption and digital static). They had me reset the SMC and the NVRAM and PRAM, but that did not resolve it either.

Has anyone else experienced this issue with their new iMac using an external display, and if so, were you able to resolve it (and how)? My iMac is otherwise perfect, so I really want to avoid sending it in for repairs if the iMac hardware is not faulty.

Thank you.

iMac, Mac OS X (10.7.1), i7 Quad (3.4Ghz), 16GB RAM, 2TB HDD

Posted on Sep 10, 2011 8:22 PM

Reply

Answer 1

Oct 13, 2012 11:48 AM in response to UltimateOwnage

I have the same issue:

Macbook pro 15" mid2011, OS X 10.8.2 connected via mini Display port to DVI to ASUS VE278Q

I use the external display as the only display, whenever I put the computer to sleep, the display cycles the "No Input Signal" and sleeps for a second (power led turns from blue to orange), then turns back to "No Input Signal"

I just got this monitor, I'm used to falling asleep watching movies, and the Mac goes to sleep when movie is done, I woke up this morning to my monitor in this cycle, very annoying.

Reply

Answer 2

Sep 24, 2013 7:29 PM in response to Cup o Coffee

Exactly the same problem here. Anyone found a solution to this? My MBP is a Late 2011 model and I'm running OS X 10.8.4.

Reply

Answer 3

taal

Level 1

4 points

Oct 28, 2013 9:48 AM in response to UltimateOwnage

I notice the discussion is going on for some years. I have a iMac 15" with thunderbold and an extra HP monitor. The monitor worked fine, but lately I start geting the same problems of the monitor cycling on and off. The monitor shows "no Input Signal" sleeps for a few seconds and turns back on. I hope there is someone who has a solution? What did UlimateOwnage, Cup o Coffee and terwin4au do to solve this problem?

Reply

Answer 4

wrxtasy

Level 1

25 points

Nov 6, 2013 11:49 PM in response to taal

I had the same problems on my Mid 2011 Thunderbolt iMac.

External monitor would sleep cycle when connected.

My only solution was to get an 3 in one Ebay Mini DP/Thunderbolt adapter then connect a HDMI to DVI cable to that, with the DVI end of the cable going into the monitor.

There must be a signal issue preventing proper sleep using Mini Displayport/Thunderbolt to Displayport connections for external monitor output.

Here is what my Systems Information Graphics/Display outputs:

Reply