After Mountain Lion Upgrade External Screen Flickers

oh..

so it didnt totally cure the flicker, but its now going after a few minutes.

interestingly enough, switching the monitor to a lower res stops it too..

switch down from 1080 to 720 and no flicker..??

and finally, while troubleshooting a different problem, I got out my EDID recorder.

putting this in line with the monitor seems to have eradicated the issue completely..

so it looks like the problem is caused by the EDID not being read properly by the mac for some reason, following the ML upgrade.

My Macbook pro 13 2012 mid have this problem after upgrade to OSX 10.8.3. Before that I havn't encounter this problem.

I am getting SAME problem.

Major screen flickers with MBP i7, 10.8.3, external Dell 24" connected via thunderbolt->HDMI in clamshell mode...

SOOO ANNOYING!!!

I've tried everything.

Anyone else have any fixes?

Help please.

For what it's worth, I seem to have resolved the issue on my end. Was having pretty much the same issue all of you were describing. My external LG display via Thunderbolt to HDMI suddenly started flickering like crazy.

After much messing around, here's what worked: changing the display/color profile in system preferences. I opened System Preferences>Displays, then I "Gathered Windows" (button in bottom right) to get my external display's Preferences window on my laptop screen, then clicked COLOR. Then I clicked on a different "Display Profile" than what it was currently set to (was on a custom profile I made, I changed it to the generic "Display."

As soon as I did that, the display was fine. What I'm guessing is that the problem may have lied in a glitchy profile preference file. Another thing I might try not is trashing my custom color profiles and resetting them.

For the record, I'm running a Summer 2012 MacBook Pro (Legacy), Mountain Lion OSX 10.8.4, Belkin Thunderbolt to HDMI Adapater, to HDMI input on an LG Flatron E2742 monitor.

I would describe the problem I was having as heavy static/flickering, multi-colored, similar to old tube TVs that weren't getting a good signal. I could see parts of the image below the static, but the digital snow and flickering were far too crazy for the display to be functional.

Hope this helps someone else out there! 🙂

Blake - I thought this was going to be a hopeful solution today on my MacBook Air mid 2012 w/ a 27" Samsung display via HDMI to thundrbolt or HDMI to DVI thunderbolt. However, it doesn't seem to be a full solution.

Have you seen success with this as of now? I'm running 10.8.5. Also, I guess it's worth noting that I've got a 27" LG as well at another location and have no issues with this, nor a 20" Dell.

I also have flicker, but its not random... it happens whenever the computer is working. If a website loads, the external flickers. When I open a new application, the external flickers... but only when its resolution is set to 1050x 1680 or 1200x1920. If I set it to 1000x1600, it does not flicker.

Here's what I've got:

Macbook Air 2.13Ghz; 4gb Ram running OS 10.9

Dell U2412M external monitor connected wwith a MiniDisplay to VGA adaptor

My question is whether or not a Apple Mini DisplayPort to Dual-Link DVI Adapter will help.

Thanks