New 27" Thunderbolt Display Flickers when attached to new 27" iMac

Bought an 27" Thunderbolt Cinema Display. When connected to my Retina MBP flickering at unpredictable moments, especially in the first minutes after starting up.

I have no idea if it's a Mountain Lion issue, since I bought the display after the new OSX.

I hope it's a software thing.

The flickering was happening with me on OS X Lion (see previous posts).

I'm using a Thurnderbolt iMac with Apple Cinema Display.

I haven't connected the display since upgrading to Mountain Lion - I was hoping the OS upgrade would have sorted it. When I've connected it up, I'll report back in case anyone has a similar set-up.

My configuration is MacMini i7 2.0GHz quad (server config). I have 27" Thunderbolt display and HDMI connected 24" BENQ monitor. I originally had flickering with just TB monitor and 4Gb RAM but this was fixed by firmware upgrade. I upgraded to 8Gb RAM added extra HDMI monitor, no issues. Then after several months I upgraded to 16Gb RAM and now TB screen flickers and in some programs iMovie for example just goes black and I have to connect remotely and reboot to get back the screen, although remote desktop shows it fine. Has anyone found any 16Gb RAM that works. I am using Corsair. I think I will back off to 12Gb and see if makes any difference. This version of the server does not have any graphics other than HD 3000 on the i7 CPU so it does use main RAM for video RAM.

I have a Mac Mini server (2011) and after upgrading to 16Gb was getting the flickering on the TB display when in dual screen mode - 1 TB screen and another HDMI connected screen connected to the HDMI port. Today I connected the HDMI monitor using a USB display adaptor from j5create and it has fixed the issue.

I have a MBP 15"(2011) and switched to 16GB and a 256 SSD and it is working absolutely fine with 2 x Thunderbolt displays.

But iam using a MacMini(2011) as well and switched to 16GB and 256 SSD as well ... but there the flickering is on.

Putting "only" 12 GB in the system, flickering stops, same with 8 GB.

I have had the same issues with my MacMini i7 server. 8Gb was fine when I was using two monitors, 16Gb flickered. I did fix it initally using a j5create usb to HDMI display adaptor but that required me to unplug it before reboots and plug it in afterwards, that was new behaviour under Mountain Lion and they have not yet updated the drivers for 10.8. So I am now trying 12Gb RAM. Did you have 8Gb on the top or bottom slot when you not no flickers?

8 GB in the bottom slot, 4GB in the top slot at the moment.

OK that is the configuration I have in my Mac Mini and so far no flickers at all.

And on my one it is running fine since may be one week ... on the other hand it would be nice, Apple would fix this problem finally

Guys, may be I found the problem's root.

I have 13" MBP i7 2.5GHz early 2011.

My MBP worked under latest release Mtn Lion and has all firmware updates.

Nevertheless I had the display's flickering with supported 8GB RAM.

I bought 8GB / 2 modules (Samsung M471B5173BH0-CH9JP), then bought 27" Thunderbolt Display.

When I worked with TD only, everything was fine, but when I used both displays and read websites with flash content, the TD flickered often. I found this thread, started memory test and my TD flickered more than 3 times per minute (with "Restoring DP Link" messages in log).

I downgraded my memory back to original 4GB / 2 modules (Hynix HMT325S6BFR8 -H9) and got not flickers even while memory testing.

I found that this modules have 16 memory chips per module instead of 8 chips in previous pair.

I took 2 different 4GB modules (Samsung M471B5273DH0-CH9 and Hynix HMT351S6CFR8C-H9) from other laptops and ran memory test using both displays (laptop + TD) without flickering.

Then I changed memory to other two 4GB memory modules with 16 chips per module (Samsung M471B5273DH0-CH9) and ran memory test without any problems and flickering.

Hi Have you tried 12 Gb using mixed chips. I changed to this configuration on my MacMini using 8Gb in the bottom slot and since the change I am running two monitors without any flickering at all.

I get occasional flickering with 12GB but not often.

I'd note that the flicker is also there when connecting to other displays via the Mini Displayport—it's not only Thunderbolt displays. In my office we have conference rooms with large monitors and when connecting via Mini Displayport (HDMI) there is terrible flicker. Connecting via VGA there is no flicker.

Ever since I got a new MBP with the new thunderbolt port, any monitor I hook up to the port will turn on and off repeatedly for several minutes before becoming stable. The monitor may turn off later, but usually stays stable after it has been connected a while.

The monitor will drop out, showing the "no signal" text, then even going down to sleep mode (green light turns to yellow).

I took the MBP into the genuis bar and they diagnosed a bad mother board. After it was replaced, the problem stayed the same, so it is not the mother board.

I thought it might be the thunderbolt adapter, but I have two of them and the problem occurs on three different monitors with either ofthe adapters. None of the monitors is a Thunderbolt monitor. I use the VGA port.

The MBP screen is not affected.