Q: Thunderbolt Display turns off randomly

Great @graystate! I am very glad for you!

I should have posted an update a month ago, about my situation. I pushed Apple Care over the phone, to a Senior advisor, and I had an interesting chat. No solution, of course, no money back after 2 weeks of purchase, etc... but still I made my points very clear and heard.

So I got to a different Apple Service Provider, with both the MBPro Retina and the Thunderbolt display. They did not reproduce the problem in 2 days, but they applied firmware updates for the MBPro AND the Display. I thought it has been made already by the first Service provider... any way, there was the Mountain Lion update 10.8.3 as well.

Then I cannot say exactly which one made good, but the issue did NOT occurred since the 29th of March '13 !! That is a big relief, I must say. No single issue, and I sometimes let the computer and the screen on for 10 hours without going to sleep.

I will keep in mind to take the Apple care extension (purchase available for the first year after initial product purchase). I am not sure if I will go for the display only for €99, or for the MBP + display for €349... If the issue is more with the Thunderbolt protocol and wiring (maybe to young to be reliable enough, I should have know that with Apple, never buy the first version ;-) than the display itself, how to know on which side the issue is???

Did some of you guys updated as well to 10.8.3?

And did you try the firmware updates (maybe directly from the apple website, not sure if the automatic software update is 100% reliable)

http://support.apple.com/downloads/#thunderbolt

I was having a frustrating problem with my 2012 MacMini. When I had two monitors attached to the computer, randomly over the course of the day, the Thunderbolt display would go black.

2012 MacMini 2.6 GHz i7

16GB OWC RAM

27" Thunderbolt Display

24" Apple Cinema Display via the included HDMI to DVI adapter

Usually once a day, though sometimes twice, the Thunderbolt display would go black. The Cinema Display would stay lit up. I have a LaCie Thunderbolt hard drive hooked up to the Thunderbolt port on the monitor. The hard drive would continue to run. There didn't seem to be any trigger or set time for when it would happen. Sometimes it would go black after an hour. Other times, it would be after 6 or more hours.

Putting the computer to sleep by hitting the power button, waiting a moment and then waking it up by pressing the button again would turn the monitor back on. A full restart worked as well. I quickly learned a very helpful key sequence: Cmd+Fn+F1. (I have my Function Keys set to actual Function Keys so it might just be Cmd+F1 for others.) This toggles the Mirror Displays function that you normal get to in the Displays PrefPane. That would allow me to safely save or shutdown things I was working on since I could now see all windows and the menubar on the Cinema Display. Then I could use the Sleep method or a Restart to turn the Thunderbolt display back on.

This had gone on for several months. I finally unplugged my Cinema Display since it was such as hassel and I never knew when the problem would hit. The recent Thunderbolt Target Disk Mode Firmware update gave me hope that there might be a fix. After updating the firmware, I plugged my Cinema Display back in. Within an hour, the Thunderbolt Display went black again. A Google search lead me to this thread and I finally had hope that I might have a solution.

I saw the posts about people having trouble with OWC RAM that was fixed by installing Crucial or Kingston RAM. I immediately ordered the Crucial 16GB kit from Amazon.

http://www.amazon.com/gp/product/B008LTBJFW/

I installed the RAM at 3pm yesterday and hooked up both monitors. I worked from 3pm until 7pm without any problems. I started work at 9am today. It's now 6:50pm and I haven't had a single problem. It's very exciting! I'll need to see over the next few days if my Thunderbolt display goes black before I declare it a sucess, but I'm hopeful.

A second day of work has gone by on my computer and I had zero problems. This looks like a very promising fix.

I would like to add one note of clarification on my previous post, the Thunderbolt display worked very well for me with OWC RAM when it was the only monitor attached to the computer. It was only when I had 2 monitors hooked up that the Thunderbolt display would go black one or two times per day.

My problem ended up being a problem with the display cable. Had it replaced and it's as good as gold now.

My NON Thunderbolt display will also go black ramdomly! It happens when it's on all day. Not in a hour or so.

I have two EIZO displays connected to Mac Mini late 2012, the first through HDMI->DVI adapter, the second connected to the Thunderbolt AJA IO XT device, via Thunderbolt->DVI adapter. So the display is last in the chain. Pulling the Thunderbolt cable out/in will take the screen back.

Have all updates installed, and yes, I have 16 gig of OWC memory. I thought that was the better ones for mac Mini...

Hmm... yeah, okay, this is interesting. Is that RAM CL9? It's been mentioned before that this is likely a timing issue, so the CAS level could be the problem. If it's not CL9 then you could get these problems -- nothing to do with the display, per se. The RAM would test fine, since it's not a question of it failing in any way...

[EDIT] Okay, just looked around OWC's site, and it look like it's CL11, which might be the problem. I wonder if they're testing it with TB displays? (That is, since they certify it for these machines...)

Well, I don't know what CL9 is, and I can't find it in the specs, but you can see the RAM I have on the following website:

http://macupgrade.eu/catalog/owc-geheugen-16gb-2x8gb-sodimm-pc12800-1600mhz-p-84 4.html

Yeah, looking at that link it is CL11, which is... well... 2 slower! ;-)

The CAS level is a latency rating. I don't honestly know the gory details about it, but I'm sure someone else here can fill you in on that. But being related to latency, it definitely involves timing! I believe it's an attribute of the controller chip on the DIMM.

...oh, and just to contextualize this; I had the problem too, but got rid of my TBD a long time ago. A few months later I discovered the CAS level thing, so I looked into my own 16GB kit -- it is CL11. Could be a coincidence, but probably not. I'd be interested in trying CL9, but I don't have the TBD any more, so it's a bit of a moot point.

But jonmichaels above, posted a link to Crusial memory on Amazon, and that is also CL11...

And he has no problems since that change...

Yeah, CL9 is harder to find, and usually a bit more expensive. But if it works, well...

[BTW - I seem to recall that mine is Crucial CL11 as well. In on a 2012 MBP.]

Yeah, my computer has been rock-solid ever since I installed that Crucial RAM. The display hasn't turned off once since May 16.

I can't speak to the technical differences between the OWC 16GB kit and the Crucial one, but if you're going to use 2 monitors on your Mac Mini, it's probably a good idea to go with the Crucial (or possibly the Kingston that was mentioned in an earlier post).

Have a late 2012 Mini connected to a Thunderbolt Display and a Dell Untra Sharp 2408WFP. I upgraded to 16 GB of OWC memory and started to have blackouts of the Thunderbolt Display. Removed the OWC and installed Kingston and have not had a problem since.

I can reproduce the blinking screen by running memtest application like "Rember"

Can everybody who "hasn't had a problem since" post the CAS latency on their RAM? The brand doesn't mean much at all, but if it can be determined that everybody who has been "cured" is using CL9 RAM, then that would (probably) be useful.