Target display mode blinking black

I am also having this issue with two 27in iMacs. One is a CTO that I just got last week 3.5GHz i7, GTX 780M and the other is the model before 3.4GHz i7, GTX 680MX. The older iMac is set to target display mode, connected to the new iMac with a brand new thunderbolt cable ordered from Apple. Both are running OS X 10.9.2. It happens every couple minutes and can be really annoying. Doesn't matter what App I am using but does seem to happen more with intensive processing.

Apple please fix this issue soon or I will be forced to return both iMacs and find a better solution.

I am also having this problem, like everyone else. Retina MBP, mid 2012 with a bit older iMac in TDM (mid 2009, i think - but it does have thunderbolt).

Has anyone heard anything back from Apple? Does anyone think that there will be a solution, or are we all giving up on this together?

-glass half empty today

This thing is killing me. I upgraded to Mavericks and it didn't help. I get this happening A LOT, sometimes multiple times per minute. Then i can go an hour, but then again. As everyone said, it is dependent on cpu usage.

So when i'm taxing it, it happens over and over and over again.

Really surprised that Apple has been so silent about this. Losing faith...

I have this problem too - mid 2001 iMac, and a MBP Retina 15 that I bought new in April 2013. It doesn't happen frequently, but enough to really be annoying.

This still happens at least once, maybe twice, whenever the iMac stays in target display mode for more than a few minutes. Using 10.9.2. Mavericks did improve the problem, but it's still there.

I have the same issue, MBP retina mid 2012, thunderbolt (2m cable) to iMac mid 2011. retina running mavericks, imac lion. fades to black and fades back with occasional stripes and flickering across the screen. takes a second or two and happens randomly. would love to see this fixed.

Same issue here. Display flickering often on a MBP retina early 2013 and mid-2011 iMac. I also lose my cursor when it flickers about half of the time. I have had the graphics card replaced and it did not fix the problem.

I am running 10.8.5 on both machines and I work from home and having the screen go black while working in Photoshop is quite annoying. I want to do a clean install of Mavericks on both before I open an AppleCare claim but it seems like there is no solution at the moment. Thank you all for the info and updates. I know this issue is driving us all nuts! Hopefully this issue will be resolved soon.

Yep. Same here - 2x iMac 27" One late 2013, the other (TDM) machine mid 2011 both running Mavericks 10.9.2 connected via 2m thunderbolt cable. TDM machine "black screens" regularly and randomly (it must be at least 20 times a day).

TDM is a great idea but it does need a bit more thought given to it - Why can't I (given that the two machines are connected by a thunderbolt cable) use the hard drive of my TDM machine as a backup device for example?

Well I don't want to jinx this but I think I fixed the issue by doing a clean install of 10.9.2 on my iMac. I have left 10.8.5 on my MBP because it is my work machine but I have been connected from my MBP to my iMac via TDM for 3 hours and I have not had it flicker at all. Before it was rediculous... It would happen anywhere from 25-100+ times a day. Sometimes a half dozen times in a minute.

I have done a number of things to try and trigger it to flicker with no problems. Generally video or screen sharing via Skype would make it flicker wildly. No issues thus far! Well the only bug is I can no longer adjust the iMac screen brightness with my USB keyboard but I can live with that.

Knock on wood... I will repost if it starts flickering again.

Dammit... it took 4 hours but it just flickered. I reveal iTunes from being hidden and when I clicked the pause button it flickered. Still it is 99% better than it was before. I will test it for a week and update at that time. Thanks all.

Sorry for the late update... I have installed 10.9.3 on my laptop and the flicker is still present.

My iMac and MBP are both running 10.9.3. The flicker is still present but not nearly as bad as it was when they were both running 10.8.5. I did a clean install on both machines.

It seems like the flicker was less frequent with my iMac on 10.9.3 and my MBP on 10.8.5. Anyoneheard anything new on this issue? Thanks.

Just throwing my name into the pool of people having this issue as well. Retina MBP with a 27" iMac (software up to date on both) just like many others. I'm sure this is an OS bug that will need to be fixed in an update, but can't hurt to let Apple know there are more people experiencing this.

Throwing also my name into this sorry pool. I have recently bought a brand new iMac (late 2013) running on OS X 10.9.4, then found clever to buy a used iMac (mid 2011) running on OS X 10.7.5 for the same price of a brand new Thunderbolt display, in order to use it as as a second display for my Late 2013 iMac, using TDM with a 2 meter Thunderbolt cable. I carefully asked for the feasibility of this BEFORE buying the second iMac in my Apple Store (premium reseller). Answer was yes, go for it ! Everything went well, even succeding to also share the 2nd iMac hard disk and superdrive while in TDM, using my local Ethernet network. However, when starting to work, the 2nd display started to blink black as described in many of the previous posts here. What makes me a going mad, is the fact that the guy at Apple store didn't tell me there is this running issue... I would have bought the Thunderbolt display, then, since this was my initial plan. I am going to rattle their cage a little bit and see what happens.

Follow up from my latest post:

I went to my Apple store, and asked the Support technician about this issue. The answer was he (and his more experienced colleague he checked with) hasn't heard a thing about this issue. He suggested I bring the two iMac for them to check, I am not very eager to do so, since it is quite a pain to bring two 27" iMac to the shop, they don't even have a nearby parking lot...

Whatever, I kept an eye on the blinking happening, and I discovered this: on the console of the iMac used as the Target Display, when the blink occurs, the following message is recorded:

22/07/14 20:26:21,000 kernel: IOThunderboltSwitch(0x0)::listenerCallbackStatic - Thunderbolt HPD packet for route = 0x0 port = 11 unplug = 1

I've checked 3 times just after a blink, always this very same message can be seen.

Would anyone have a clue to decipher this message ?

Testing...