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

As a follow up to my previous post (flickering occurs since upgrading to Snow Leopard), I have personally seen this on 2 other mac books and talked to several others - all are getting the flickering since the Snow Leopard upgrade.

I surmise this is somehow related (even though all the examples I mention were not 27" iMacs). Software/driver issues? Just a thought.

Just an update on mine: i7/8GB
I have at this point chosen not to have it DOA'd but I'm in the group that mine is appears fine for days on end and once the flickering starts, a reboot will fix it for a few days.

I just set the screen to never turn off and the machine's been going for almost 7 days days now without issue. I've changed the power saving settings again to power down the screen after 1 hour of no use so we'll see how quickly the flicker returns.

My guess: firmware/driver issue and Apple will release an update within a week or two. (That's my hope anyways...)

My week 50 iMac has arrived intact. It powered up successfully and is in the process of migrating data from my older iMac. Nothing out of the ordinary to report thus far, but I think I'll be holding my breath for a couple of weeks.

Well the 1 hour long hardware test showed no issues so according to the tech its not a hardware problem. Yeah right. If they had a test to detect this problem we wouldn't have the problem in the first place.

I did notice that a restart seems to remedy the issue. Also, periodically I have an issue that opening a file browser window takes forever. Restart seems to fix that as well. Really strange.

Since I'm past the 14 day window I'm just going to wait it out for now....it's only happened sporadically and I don't want to take the computer in just yet.....its huge!!

Joe

{quote:title=thxdude wrote:}My guess: firmware/driver issue and Apple will release an update within a week or two. (That's my hope anyways...){quote}
Unfortunately, optimistic Apple fans were saying that a month ago, and no such luck to date.

Another user here just chiming in...

My 1 day old 27"i7 has just started exhibiting flickers & total screen blackouts. The flickers are random and occur at various areas of the screen on average 2 to 3 times a minute, whereas the blackouts are less frequent - noticed 2 so far in the last 20 minutes.

I also have a pixel sized piece of dirt stuck to the inside of the screen(!) and the display is showing some (albeit subtle) yellow tint toward the bottom of the display.

My serial is W8950xxxx.

{quote:title=Chew.it wrote:}My 1 day old 27"i7 has just started exhibiting flickers & total screen blackouts. {quote}
Thanks for the update. In short - new deliveries still showing the issue.

Chew.it wrote:
Another user here just chiming in...

My 1 day old 27"i7 has just started exhibiting flickers & total screen blackouts. The flickers are random and occur at various areas of the screen on average 2 to 3 times a minute, whereas the blackouts are less frequent - noticed 2 so far in the last 20 minutes.

I also have a pixel sized piece of dirt stuck to the inside of the screen(!) and the display is showing some (albeit subtle) yellow tint toward the bottom of the display.

My serial is W8950xxxx.

I think that the real proof, if the problem will be fixed or not, will be on iMac performances that users will receive next year. That is those iMac that will be assembled during these days. We need a two/three weeks. All of this only if it's a hardware problem. Who knows?!?

Crikey...a week 50 machine? I'm thinking the one I have on order will be a week 51 machine...

Mainly I'm assuming its 'software' controllable due to this discussion thread on a PC side:

http://www.tomshardware.com/forum/273975-33-solution-screen-flickers-cards-4800- series

The verdict seems to be two fold: frequency of the video card and also the screens connected.

The tech I spoke to seemed utterly convinced that it was a software issue.

Do you have anything installed? CS4? MS Office?

Thanks.
Joe

I don't know if its relevant but somehow these messages have to be related: during flickering I got them into system log, after stop and wake up, no flickering and no more occurrences of them:

Dec 16 20:51:40 host645-1 Safari[378]: unknown error code: invalid drawable
Dec 16 20:51:40 host645-1 [0x0-0x2a02a].com.apple.Safari[378]: Wed Dec 16 20:51:40 host645-1.my-host.name-nere Safari[378] <Error>: unknown error code: invalid drawable

Tons of them but just during flickering issue.

Ideas?

I think this is an excellent assessment of the problem. I received my i7 ten days ago (Dec 7th) and it works perfectly except for the occasional flickering and 1-second blackouts. I was considering calling apple to request replacement, but it seems replacements at this time bare the same display problems.

After reading your reflections on the problem, I will wait for a few weeks more, until Apple nails down the issue(s), for it is obvious that at this time it has not resolved the problem entirely. Otherwise those who received replacements would have reported success instead of further frustration. At this point, I will wait for apple. It must resolve the problem very soon. Otherwise, it will become a huge bad publicity problem and it will hit their shareholders value much more than the cost of the problem itself.

I was wondering.. Could the flickering be caused by the 3d acceleration which Mac Os X uses? I have seen weird anomalies way back with linux and compiz which utilizes 3d acceleration aswell.

If someone can try to boot the iMac in safe mode (hold shift right after the chime and wait for apple logo) and see if anything changes (for the better) that could shed some light on the issue. In safe mode no 3d acceleration will be used.
I know it will take some time to be sure, but it doesn't hurt trying I guess.

So I think to move things forward, if someone with a known GOOD machine can post their machine info for Display/Graphics here, we can compare if the new machines are shipping out with different versions maybe. Again, I doubt this is the case and its a matter of Apple releasing a firmware/driver update but it will give us something to chew on in the mean time

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