Thunberbolt Display flickers off at random (Yosemite)

To verify if updated go to about this Mac, more info , system report and under thunderbolt bus it should show firmware v 23.4 and under TBD the port micro firmware should be v2.0.7.

If you still have issues I guess this update did not work.

Same problem here. I've got a new Mac Pro here and one 27" display connected to it, via Thunderbolt. I tried installing the update and it says, that I already got it. The firmware version of any of my three Thunderbolt Bus entries says I got v19,2. The Thunderbolt Display version (Port Micro Firmware Version) is at v2.0.7 tho.

Dunno what to do here. 😟

Try to turn of "Automatically adjust brightness" in Display Preference. That helped me.

I have exactly the same problem with my Apple Thunderbolt Display (27 inches), the problem started appearing right after I did apply the firmware update V1.2 to the monitor which was made available by Apple last November (my monitor was working flawlessly before applying this firmware update so I am pretty sure there is something wrong with this firmware version and this is the cause of the problem). Does anyone here did apply this firmware as well?

I'm having the exact same problem. I have two monitors, both through thunderbolt. One is an Apple thunderbolt display, and the other is a Dell U2410 through a thunderbolt->DisplayPort cable. Each monitor independently will go black for a half second. The main Thunderbolt display does this more often than the other. I also was hopeful about the firmware patch, but unfortunately it did nothing for me. I also noticed this problem start up after upgrading to Yosemite.

Sorry to resurrect this comment, but this might be the only thing I have not tried in the past year. I have a Mac Pro with two TB Displays, both of which flicker as described in this thread and a lot of other places. Here's what I've gone through with 3 Senior Apple Techs and have had no change...

- They suggested it was "dirty" power and recommended I purchase a power conditioner UPS ($160, no change).

- They suggested I buy 2 Apple brand Thunderbolt cables and use those instead of the ones attached to the displays ($78, no change).

- Several Genius Bar appointments for stress tests, some taking as much as 2 hours each

- Several times capturing data and sending to their engineers with several suggestions, including those above (no change)

- Replaced my Mac Pro with a completely new machine ($0, no change)

I don't understand how this can be something that I can easily search for and find (not suggesting it's widespread, but it's not unknown) yet the engineers and techs at Apple can't figure it out. I feel a lot of regret buying this machine for my business because it's been a daily reminder of how much I've spent on a faulty device that makes work a chore.

Thanks to all of you for the suggestions you've made to me or others... let's hope we can figure this out!

I just bought (March 2015) a MacPro and Apple TBD--major outlay of cash. The screen flickers as you describe.I've noticed that on occasion when the display goes to sleep that hitting the space bar "wakes up the mouse cursor" but the screen remains otherwise blacked out for 10 seconds (hitting other keys during this time appears to have no effect).

My call to Apple Tech was disappointing. They had me plug and unplug the monitor and then reset the PRAM. The tech guy said that his senior manager swore this would end the problem. It hasn't ended it. Perhaps we're learning why Apple just switched to USB-c. Maybe they can't make TB live up to the promises they've made for it.

Like you, I really hope Apple doesn't abandon those of us who paid money for TBDs.

I would suggest doing what innocentius recommends. Since I ticked that checkbox in the display settings, I haven't had a single flicker... I know it has only been 24 hours or so, but that's huge considering what I've been through in the last year... and I've been on my computer for 16+ of those hours!

I'll give it more time and report back...

I just bought my Apple 27" Thunderbolt display and also experienced the flickering. I read on this forum that some people used the thunderbolt cable (that they sold me and I couldn't figure out why once I unpacked it and saw the hard-wired connection). Once I attached the thunderbolt cable the flickering went away. I wish they would have explained that I needed to use this cable instead of the hard-wired cable. I think Apple has some work to do on this. For $1000 the hard-wired cable should work. Also the magSafe power cable didn't fit my port as my MacBook Pro is not brand new. Aargh!

The "Automatically adjust brightness" setting also helped me and my brother -- turned it off and no more issues for either of us -- both had tried a bunch of stuff (replacing cables / etc...)

Then pulled the power to the screen - and all is now good..