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

Sorry for posting yet another thread to this post, but reading the many posts in this thread I am unsure which solution/approach will resolve the flickering issue I am experiencing.

I recently received a newish laptop with MacBook Pro for work

• 2GHz, Memory
• 4GB 1333 Mhz DDR3
• AMD Radeon HD 6490M 256MB
• running Mac OS X Lion 10.7.5

I have it hooked up to an older Cinema Display (2008) 24 inch

AMD Radeon HD 6490M 256 MB graphics

It flickers every 3-4 minutes and then eventually turns off.  I went to the apple store and they indicated my computer is too fast for the monitor...but since I did not bring in the monitor to demonstrate the flickering, it was an educated guess.

Can someone confirm if this is indeed the case and/or if there is anything I can do to resolve this.  I am trying to upgrade my monitor for work and they think it may be the video card in my laptop..which has never failed while projecting to an LCD projector.

Plead advise!

This has been driving me nuts since I got my Mini in late November.... I did do the 16GB upgrade from OWC, so... I guess we're stuck until Apple finds a fix....  Bummer!

Thanks for pushing them on this!

I am really happy I came across this thread. It's a true blessing. I was ready to purchase the 27" Thunderbolt Display for my Mac Mini (with Corsair 16GB), and now I know I still have to wait ...

I use the TB display with my mac Mini and it works great.  No issues.  The "fast" speed of the computer should have no impact on the display working or not.  The flickering is caused by something else.

@tbirdvet

How much RAM do you have?

Started with 4GB (stock) and TB display and all worked great.  Recently upgraded to 16GB for faster processing and all is still great.  I have the I7 2.6Gz Mac Mini

@tbirdvet

I have 2.3 Gz Intel Core i5 with Corsair 16GB and a generic Samsung monitor, which I was going to replace with a 27 inch TB. After reading this thread I was going to wait till June, as Mac Rumors predicts something new to happen (http://www.macrumors.com/2013/01/14/apple-thunderbolt-display-supplies-begin-run ning-short-at-third-party-resellers/),... but now I am confused...

I'm sure the next TB display will be built on the new iMac chassis which will be thin and Apple will delete the FW800 port on the present TB display but if needed you could use a TB port to FW adapter.  I got tired of waiting and I knew the present design was proven out so I bought the present TB display and I use the FW800 port for my External HD (Time Machine)

I bought a 27" TBD for work and liked it so much, I decided to get one for home. It flickers occassionally when I plug in to one TB port, but if I switch to the other one it seems to settle down. Note this doesn't happen at work, which makes me think the quality control on the monitors may not be good. If it keeps happening I'll have to take it back!

I'm using a mid 2012 MacBook Pro Retina, 16 gb ram

@orchetect: have you seen any improvments with the latest updates coming from Apple about the 16 GB two monitors issue? It seems you were saying that using one TB monitor with 16 GB has no flicker, can you confirm that?

Thanks!

My monitor has settled down. It's working consistently well now in either port. If it changes I'll update the thread!

C

To anyone who is still having this issue, try resetting the PRAM. The PRAM stores hardware data as well as video data in it, and if it's still using the PRAM data from older RAM cards then this can cause a minor incompatability, resulting in graphical errors such as the described flickering.

You can reset the PRAM by following these steps:

1. Shut down the computer. 
2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4. 
3. Turn on the computer. 
4. Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears. 
5. Hold the keys down until the computer restarts and you hear the startup sound for the second time. 
6. Release the keys. 
7. Repeat this restart process three times to fully clear the NVRAM / PRAM.

Thanks MrMusAddict, resetting PRAM did the trick for me with my MacBook Pro 13" connected to the Thunderbolt Display.

Martijn

Thank you sooooooooooo Much... this has been driving me nuts and put me through 2 cables trying to figure it out, but this seems like it may have worked!

Excuse me, for may be dumb question, but reset PRAM operation need to be done without connected thunderbolt display? Or I need connect it and then reset NVRAM / PRAM 3 times?

I reseted it one time, but it didn't make the trick ( Monitor is still flickering