27" Cinema display flickers when woken from sleep

O.k., so I'll just give an update here in case anyone else suffers the same problem sometime.

I tried the 27" Cinema Display on my MacBook Pro, and there was no flickering.

........so it wasn't the display..........

I reset the PRAM and SMC, no change.

I removed and re-seated the graphics card, no change.

I re-loaded Snow Leopard from the original discs, and the flickering stopped.

I updated all the software (re-loading from discs reverts to an earlier software version), and everything is still o.k.

Problem solved!

Must have been a glitch in the software somewhere, and a reload of the OSX got rid of it.

Relief!

Bob.

Hmmm.........it appears I spoke too soon.........

The first few times it woke from sleep, sure enough the flicker had stopped. Now I notice that if you sleep the computer for just a few seconds, there's no flicker on awakening, but if I leave it to sleep for a while, the first time it re-awakens, I get the flicker again (before, it flickered every time).

I've backed out to a previous version of OSX now (10.6.4). I'll see how that goes.

Bob.

So, now that I've backed out to an older OS (10.6.4), I haven't had any flicker at all when I wake it from sleep.

I've tried it from a few seconds asleep to over 2 hours, and it seems o.k.

I'll continue to run it like this for a couple of days, then I'll update the OS, and see if the flicker comes back.

Bob.

Right.....I ran 10.6.4 for a day with no problems, so I updated to 10.6.6 yesterday, and have run with that for a day and a half, and haven't had any problems with screen flicker when the computer wakes from sleep.

I'll run with this for another day, then update to the latest OS and see if the flicker returns. If it does, it's obviously a bug with the latest OS.

Bob.

O.k., so I updated the OS to 10.6.7, and ran that for a day with no issues, so I updated to 10.6.8.........and the flickering returned.

Therefore, it must be a bug with OSX10.6.8.

I'll re-install from the Snow Leopard disc, then combo update to 10.6.7, and report this as a bug.

Surprised no-one else has noticed it...........

Bob.

So I've now gone back to 10.6.7 and the flicker has stopped, so 10.6.8 is at fault.

Has anyone else noticed this, or am I the only one?

Bob.

O.k., so I'm the only person in the entire world with this problem............

Interestingly, I was in the Apple Store yesterday, and I tried out the Mac Pro with 27" Cinema Display (more or less the same setup as mine).

When I woke the screen from sleep (several times), it didn't flicker.

However, when I checked the OS version, it was still running 10.6.7!!!!

Now why would they not upgrade?

I asked the guy in the Apple Store, and he said all of the machines are running 10.6.7, none of the stores have upgraded yet.

Odd..........I wonder why not.

Bob.

O.k., so I've been messing about with this some more.

First, I trued using an HDD as the bootup disc, to prove that it wasn't the SSD at fault. It still flickered.

Then, I tried changing the output resolution, and BINGO! In every resolution except the top 2560 x 1440, the flicker does not happen.

Therefore, the problem lies with the fact that Lion (and 10.6.8) has problems with the highest resolutions when the screen wakes.

I'd love to hear from someone with a 27" cinema display that shows the same problem (or 27" iMac, maybe?).

Bob.

Thank you, thank you, thank you. At last someone has put me out of my misery.

I also have the 5770 video card. At least I know it isn't my hardware now (like the Apple Support guy suggested).

I'm now going to go back to 10.6.7 (again) to get rid of the flicker. Lion doesn't hold enough adavantages (and it is full of bugs) for me.

Let me know how you get on. I'll contact the Apple store and see if they've got Lion loaded on their Pro yet, then try that one.

Thanks again.

Bob.

Just a thought.........if you're thinking about swapping out the 27" displays for TB displays, you will need a TB compatible computer, or they will not connect (according to the Apple Store).

Bob.

According to the Apple store, system requirements are;

System Requirements

• Thunderbolt-enabled Mac computer, including MacBook Air, MacBook Pro, Mac mini and iMac
• OS X v10.6.8 or later

and the connections are;

Cables

• Built-in Thunderbolt cable
• Built-in Universal MagSafe cable (up to 85W)

all of the other ports appear to be outputs, so I think you would need another graphics card (which isn't available yet).

I've just confirmed that the display Mac Pro in the local Apple Store has Lion on it now, so I'm going to have a play at the weekend.

Bob.

Another thought..........I can't see anywhere that the MacPro is actually compatible with TB........even the latest ones (mine isn't).

Bob.

Update:

I've now been to the local Apple store, and tried their display Mac Pro/27" Cinema Display combo, and guess what.......the screen flickers on wake-up.

I asked the guy in the store about it, and he says "oh yes, I see that. No-one has noticed that before, I wonder if mine does it at home".

I tried the Mac Mini with 27" Cinema display, and the 27" iMacs, and they were o.k. (no flicker).

So, this only affects Mac Pro's running 2560 x 1440 resolution.

I've booked another call with Apple Support. No doubt they'll still tell me to take my computer in for testing, even though I've shown they all do it (the guy in the Apple shop suggested that, even though I demonstrated the flicker to him on the one in the shop).

I wonder how long this will take to get a software fix? Problem is, the Pro is not mass-market (like Macbooks and iMacs), so it may take an awful long time.

In the meantime, I'm sticking with 10.6.7.

Bob.