Q: New iMac 27inch screen flickering/tearing/shutoff

I just posted in the Yellow Tinge thread (none on my unit), but I'll expand my unboxing here.

I got my week 50 iMac today, ordered on Black Friday. There was about a 2" diameter hole right through the UPS Box and the Apple iMac box. Luckily there is no evidence of anything on either the aluminum or even the foamy blanket it was packaged in.

I let the iMac warm up a bit, as it was sitting in the UPS truck all day as it did it's circuit and I was near the end of the line for delivery. Got it at around 6:40 pm. There was a bit of condensation happening.

I plugged it in, booted up and got to the desktop just fine. Checked for a good 20 minutes for Yellow Tinge and really found none. Extremely pleased so far, no DOA, no cracked screen, no Hard Drive noise (Seagate), no tinge. Only 4 dead iSight pixels. One last thing to look for, and I know it may be weeks before it shows up...

I'm going to run some benchmarks and put the computer to work.

So far though after 2 hours of use, no flickers yet. But the testing comes now. I'll report back if needed.

Message was edited by: Sinstormer

Running my imac for the last few hours with no issues:

my imac details

Model: - iMac (27-inch Late 2009) (CTO)
Codename: - ?
Build Country: - Your Mac was built in Changhai, China.
Build Year: - Your Mac was built in 2009.
Build Week - Your Mac was built in week 48 of that year (November).
Production Nr.: - Your Mac was number 172 to be built that week.

for display:

ATI Radeon HD 4850:

Chipset Model: ATI Radeon HD 4850
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 512 MB
Vendor: ATI (0x1002)
Device ID: 0x944a
Revision ID: 0x0000
ROM Revision: 113-B9110C-394
EFI Driver Version: 01.00.367
Displays:
iMac:
Resolution: 2560 x 1440
Pixel Depth: 32-Bit Color (ARGB8888)
Main Display: Yes
Mirror: Off
Online: Yes
Built-In: Yes
Connection Type: DisplayPort
Display Connector:
Status: No Display Connected

Hi Mac folks... try this one...

It is obvious that the problem is GPU based. If you compare the Win user problems with your iMac probs (http://www.tomshardware.co.uk/forum/page-273975150.html, http://www.hardforum.com/showthread.php?p=1035046350) you'll see the analogy...
I hope the will be an official statement / fix!



1. First check in System>Library>Extensions if you have the following dated on September 10, 2009
ATI1300Controller.kext
ATI1600Controller.kext
ATI1900Controller.kext
ATI2400Controller.kext
ATI2600Controller.kext
ATI3800Controller.kext
ATI4500Controller.kext
ATI4600Controller.kext
ATI4800Controller.kext
ATIFramebuffer.kext
ATIRadeonX1000.kext
ATIRadeonX1000GA.plugin
ATIRadeonX1000GLDriver.bundle
ATIRadeonX1000VADriver.bundle
ATIRadeonX2000.kext
ATIRadeonX2000GA.plugin
ATIRadeonX2000GLDriver.bundle
ATIRadeonX2000VADriver.bundle

2. Activate Root account, and login as Root
3. Go get them here: homepage.mac.com/mahers/ATI.zip
4. Decompress and replace with what you downloaded in System>Extensions
5. Restart and repair Permissions

I got mine swapped mid November and restored the same as original one and run the same software.

I have not had any problems with the new one at all after a month so I still believe it is a hardware problem. I hope you all get yours resolved quickly when they are working as they should they really are excellent.

As a follow up to my previous posts :

iMac 27" 2.8 Quad Core Intel i7, 1TB, 8GB SDRAM
W8945...
ATI Radeon HD 4850 (512Mo)
ROM : 113-B9110C-394
EFI : 01.00.367

*Rare issues are flickering+blackout.*
I only discuss this type of issues.

I received the system Nov 23 and installed it with the Migration Assistant.

- Nov 30 : first flickers and blackouts (in the afternoon, system hot.

Instinctively, I put it to sleep and immediately wake it up : that cures the issue for the rest of the day.

- Dec 01 : video cam ready, temp monitoring via iStat, I booted it up and 10 minutes later (system cold) it happened again ; took a video.

http://gallery.me.com/jacques.laporte/100192

I remarked that it only affects the video card (no data lost), just like a quick sleep/wake cycle.
Same cure : sleep and wake maneuver.

It worked well 10 days until Dec 12, a new flickering solved the same way. Worked well up to now.

I have not done further investigations, cause I'm now sure that a "sleep/wake" maneuver will stop the idiosyncrasy.
I think that all the medicine is in the "wake". It kinda 'resets' or switches profiles in the graphic card (in relation possibly with memory clock).

What triggers the graphic card to this unsettled state, I don't know. It could be a high sensitivity to power line surge, other interferences, or a software issue (at the OS level) or at the firmware level (EFI, graphic card ROM) etc …

All I can affirm is that it comes randomly. Cold, Hot, doing video (DVD, IMovie) or Photoshop or just the Finder (my 3rd case) : it can happen.

The following thread, already mentioned, is very instructive : It seems that flickering is a common thing with video cards that are overclocked (customized ?)

http://www.tomshardware.co.uk/forum/page-273975150.html

ATI has documented on their Website (support section), possible causes for 'display flickers'
"There are four potential causes to this problem: 
1. Interference from nearby electronic devices (cathode-ray tube (CRT) displays only)
2. Improperly connected hardware
3. Non-functional Hardware
4. Resolution and refresh-rate not set correctly
"

Anyway, on my system, this issue is cured by a card reset (the wake action), that is to say a pure soft or firmware action.
And many others have used this workaround.

The question now is to understand why and at what level (OS, driver, video card ROM ...) the graphic subsystem sometimes loses control.
And to find a fix.

That said : it's a very beautiful machine.

Message was edited by: Jacques LAPORTE

I don't know if it's related, but I've had some issues with 'Export To PDF' and 'Save As' dialogs not rendering properly in QuarkXPress 8.12. In addition, I was encountering a problem where when launching Firefox, it would not come to the front - ie it would launch behind all other apps' windows.

Investigating the Firefox issue led me to a fix: uninstall Growl. I did this and after a restart, the Firefox issue was fixed. To my surprise so is the issue with the QuarkXPress dialog box rendering.

Also, my screen hasn't flickered since I uninstalled Growl.

Maybe, just maybe this is just another another symptom of a general graphics issue in 10.6.2?

So, if you are running Growl and are affected by this problem, maybe you could try uninstalling it and see if it helps.

As others have pointed out, it is not solved.
A standard test for the laptops displays is to connect an external monitor. If the internal display is malfunctioning then the problem will not travel to the external display.
However, if the video subsystem on the logic board is malfunctioning the problem will travel to the external display.
This reported external monitor problem was the first I have seen with this information. Unfortunately hardware testing without OS does not test attached devices like this. But, the video card in the iMac in question is definitely involved.
Yes, in some cases the PRAM reset solved a corrupted PRAM issues which can affect the display. In many cases this is needed after a migration.

Two weeks now since I got the replacement from the same batch. No flickering or yellowing issues at all. I've used Photoshop, Final Cut Express, Logic 9, and nothing seems to faze it. Still keeping my fingers crossed.

Those of you who are worried about the 14 day deadline, when I went in to get the replacement, the guy at the Apple Store told me that the deadline had been extended for the holiday season until January 15th. I'd check with your local store to make sure this applies.

I think it is really quite interesting, maybe even thrilling to try to solve the problem in a Whodunit style. However, I am sure we will not find the solution by trying to isolate a culprit. It has to be something only a firmware update, a driver update or a hardware replacement can solve. Which means: Must be waiting for Apple to come up with something.

Whenever we think we found a promising way there follows evidence to the contrary. My example, to all those who thought this is heat related: I switched on my iMac ten minutes ago, left it standing there while getting me a coffee - and returning I saw the menu bar in the middle of a flickering screen. Hadn't touched a single key, no application was running. Put the thing into sleep, woke it up ten seconds later and now it runs fine. Until next time.

To me it seems we are doing Apple's work here, on a voluntary basis. Will there be something from Santa for it at least? Steve Claus, hoho!

From what it sounds like, Apple is taking the machines back without a fuss.

Has anyone had a repair done to fix this? If so, any luck?

I received my week 50 i7 on Monday. On Wednesday the flickering started. The people I spoke to at Apple service had never heard of the problem. They were very nice. The frequency of the flickering is starting to increase.

Interestingly, the flickering DIDN'T happen the entire time I was booted into the HARDWARE TEST they had me run. Rock solid then.

Hmmm... hey! I just flickered! I wonder if it has anything to do with proximity to magnets or RF from powered audio monitors.

How close is your i7 to speakers?

Bob

I think that means they are going to send the iMac back to you. CALL THEM RIGHT AWAY! If you can explain to them over the phone that any flickering, etc. issues started occurring within your original 14-day period, they will probably let the 14-day window slide. But it would be best to call BEFORE they ship it back to you!

<Wild Speculation>

IF this issue is related to "overclocking" the GPU or in any way related to the GPU performance, a fix which "slows down" the GPU could be delivered as a "software fix".

With me so far? Fix the hardware problem by tweaking the settings with software. It's been done before.

</Wild Speculation>

So what I am looking for are some before and after benchmarks of the Video cards. ...Assuming Apple delivers a software fix... What would be a good tool for benchmarking the iMac video cards? Something we can all use, preferably something included in the OS. My hope is to be able to cry "foul" should such a solution come to pass.

Note: I am simply being a prepared pessimist. I have no reason to think this actually is a software issue or that Apple will reduce performance to recover stability.


...Discuss...

Bought a week 43 iMac 27" 3.06 GHz at the end of October. It flickered a few times per day.

Got it replaced with a week 47 iMac three weeks later. It has been nearly a month since then and I haven't seen any problems with the new machine. Hooray!

I said I would try come back to report on my results. Now I have and I'm unsubscribing from the thread

BTW, I should note that while I was having flickering issues, I read every single post in this thread. After I got the replacement machine, I don't feel the need I'm just saying that the vast majority of people without issues aren't going to spend any time here. Why would they? The problem is out there, sure, but it probably isn't a significant percentage of units sold as far as Apple is concerned. It must be cheaper for them to take the hit on all the support calls, replacement shipping, and discounted refurbished sales than to stop the production line. If that's true, it can't be that ubiquitous.

You think that there is a possibility that even though Apple knows about these problems and is working on it behind the scenes, that we will "NEVER" get an official message about it being fixed? I am one of the ones who is waiting patiently before I buy my 27" i7. If I never hear about a "true" fix from Apple, I may not buy till the next ones come out.

Lou

Message was edited by: kateeba