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

Several have posted here that they have experienced the problem while running windows. In addition to that, there are more than a few postings across the web of similar flickering problems reported by windows box users running i7's with the ATI 4850.

Apple seems to be of the opinion that it is a hardware problem since they are attempting a fix with a firmware update. While the firmware update has not resolved the issue in all cases, it does seem to have diminished the severity, and frequency of the problem for many, my own unit included, which is a flickering week 51 build, which was a replacement for a flickering week 46.

While a hardware problem may be a defective gpu, or display, it could also be something as simple as a bad solder connection within those components. Firmware updates can possibly adjust, or adapt the system to resolve some hardware issues, but not all.

jfaughnan wrote:
It seems sensible to register the problem. If nothing else it helps Apple understand how widespread it might be.

I did that myself.

I do agree that it makes no sense to return the machine unless the flickering is very severe. Any replacement might do worse.

My machine had flickering once every other day about 2-3 weeks ago, but since I moved the machine it hasn't flickered (different outlet but same mains power). I didn't bother installing the firmware update -- why mess with it if it seems to be doing well?

Modern computers are so complex I can imagine it might be any combination of several pieces of hardware and software causing the problem, including the bluetooth, 802.11n, power supply, graphics cable, etc, etc. I suspect different machines may have different combinations of precipitating factors.

Bottom line: If the flickering isn't severe, wait. There's no harm in simplifying your machine -- turn off WiFi if you use a physical cable, turn off bluetooth if you have a wired keyboard, etc.

I agree this is the way I decided to follow, I get a case number from Apple and will wait for them to find a solution. This computer is my 7th Mac and the first time I had hardware problems. I'm sure Apple didn't take this problem lightly, some people complain that Apple didn't talk about there efforts to solve this issue, I think they have legal reasons for that and imagine what could be the reaction of peoples if they tell us "We work on a solution but didn't find it yet"...

Normally I wait a bit before buying a new model, but this new machine is exactly what I need as computer, I'm a 3D artist, the i7 chip is perfect for that and I don't have a TV, I use Elgato receiver to be able to use my Mac as a TV, this machine offer me an economic solution for my need.

Like everybody I hope Apple will find a solution soon...

Here's some food for thought for those that are thinking about purchasing a 27" iMac, or are waiting for their, second, third, fourth or fifth replacement.

When will it be safe to purchase an iMac? When will we know that Apple has fixed the issue?

Simple, once you see refurbished 27" models in the Apple Store.

I've purchased a number of refurbished Apple products and I've never had any issues with them, from a MacBook to a Mac Mini, all are still working fine. The Mac Mini is a G4 revision one model.

Refurbished items likely have a much more rigid quality control review process. You know each item has been fixed and tested by a qualified engineer. Apple will not sell a refurbished product unless they know it is in complete working order.

So, once you see the refurbished 27" models for sale (there will be a lot of them I suspect), that's your sign to purchase your iMac.

Me, I'm a sucker, I'm waiting for my second replacement machine. I'm hoping it takes a while to ship, maybe by then Apple will have started selling refurbished models.

/kevs

pazuita wrote:
Several have posted here that they have experienced the problem while running windows. In addition to that, there are more than a few postings across the web of similar flickering problems reported by windows box users running i7's with the ATI 4850.

I'd like to add informations about my experience under Windows Vista, installed via Bootcamp. My unit was flickering and shutting down under OSX.

UNDER WINDOWS VISTA :

1 a - My windows task bar started to be relocated within the lower first third of the screen (instead of it's normal location at the top of the desktop).

- Right under the relocated taskbar, I've got some vertical bars, 1 inch height, from left to right sides of the screen.

-

GUYS WE NEED TO FOCUS ON TEST TO LOCATE THE ISSUE, AND REPORT OUR FEEDBACK HERE.
THX

pazuita wrote:
Several have posted here that they have experienced the problem while running windows. In addition to that, there are more than a few postings across the web of similar flickering problems reported by windows box users running i7's with the ATI 4850.

I'd like to add informations about my experience under Windows Vista, installed via Bootcamp. My unit was flickering and shutting down under OSX.

UNDER WINDOWS VISTA :

1 ABNORMAL TASKBAR RELOCATION
a - My windows task bar started to be relocated within the lower first third of the screen (instead of it's normal location at the top of the desktop).

b - Right under the relocated taskbar, I've got some vertical bars, 1 inch height, from left to right sides of the screen.

c - Strange behavior of the cursor : My relocated taskbar acting like the top of the sreen (Cursor desappearing when going down the screen and reappears at the top of the screen).

2 FLICKERING AND BLACKOUT :

a - Flickering : I didn't see any kind of flickering under Vista, but I can't be sure there was not, because I wasn't in front of my computer all day long.
b - Blackout : I just noted some issues when trying to wake up from sleeping mode _of the display_, taking a lot of time to wake up, or didn't wake up at all (computer seems to be on, but the screen stays black).

CONCLUSION :

Even if the symptoms seems to be a little different under Vista, compared to what I've got under OSX, There's cleary a "display" issue. It doesn't look like a software issue, BUT, as long as I was using Bootcamp, i can't affirm this is hardware issue for sure.

We now need the feedback from someone who's running Windows on his iMac BUT WITHOUT USING BOOTCAMP.

I'm thinking about something never mentioned on this thread, the EFI. We are talking about GPU bios update, but what about something as important as EFI ?

++ EFI is kinda "interconnected" to almost all important components of the computer, and we have hard time to locate the origin of the issue (multiple factors and components could be involved). I don't have my computer anymore, so please, if someone can workaround the EFI...It could be great ++

I temporarily fixed my I7 27". Nearly 3 days over 16 hours use without an issue.

Mike

Folks

I have a week 48 27" imac, which I got late November - and despite a once 'possible' screen flicker I have had no problems. The idea that it might be a power issue is a possibility...has anyone tried shifting their flickering imac to a different building/power source? Are all these machines with problems running 240v or 120v or a combination - is there anything common here as regards to power?

I have an inline UPS with a recorder. I was having trouble for about a week before I reset the computer. I checked the log of the UPS and during periods of my problems the power was conditioned without any fluctuations. Now other folks might be having some issues with power, but I am very sure I was not.

Mike

I received my replacement iMac Friday before last, applied the firmware update, and had not seen any problems until today. The screen blacked out, followed by some horizontal tearing, and ultimately the dock appearing about 3 inches from the top of the screen. I phoned tech support, and have received a second RMA. I honestly don't know what to do. I know that Apple is working on the problem, but they appear to be stumped. I think if I could get an assurance that the clock on my Applecare could be reset to the date when the problem was resolved, I'd keep my iMac in the hope that the problem would be resolved.

ok, if it's not power, then it really smacks of a timing problem somewhere on the card and the display.

Sending mine back for a refund as there is no other way hope your not past your 14 days!

The reason allot of people are not noticing this issue is because they place their screen to sleep via energy saver. Therefore no one is taking it serious and is possibly a wider issue than reported. I found this to be so on two of my clients machines. Both had this issue but actually never noticed it (hard to believe I know).

UnixToy wrote:
The reason allot of people are not noticing this issue is because they place their screen to sleep via energy saver. Therefore no one is taking it serious and is possibly a wider issue than reported. I found this to be so on two of my clients machines. Both had this issue but actually never noticed it (hard to believe I know).

Sorry to spoil your discovery, but "sleep" is the very first thing that I disable on all my Macs - I use my i7 iMac for music production and I am yet to see a "flicker" (week 47, 4 weeks of heavy use)...

I'm also week 47 and i have no problems.

I do have wireless & bluetooth disabled (because i don't need them right now)

Did anyone tried to disable everything that isn't needed like wireless, bluetooth or something else and tested if the flickering is the same?

Gille,

I'm also in Belgium and have a week 50 27in i5 that only shows VERY occasional flashing with the wireless disabled. Bluetooth is enabled because of the wireless mouse and keyboard.

If I enable the wireless, the flashing, blackouts and screen shifting come back.

The update has been applied but I haven't done the various resets yet.

I'm coming to Macs from PCs (yeah, my first Mac!) so I'm in the habit of turning it off at the end of the day.

But the point of disabling features I paid for is disagreable, even if I don't need them at the moment.

I haven't called Apple yet about it. Waiting to see how this works out.

Russel