535      iPhone_iPad_Mac_apple

2011 iMac 27 graphics card problem?

After updating to Mavericks I have had some sporatic, multicolored, blocks appearing and flashing on my display.

Does anyone have any idea what could be causing it?

<Edited by Host>

I have the same exact iMac (Mid 2011, 27in, 2.7GHz Core i5, Radeon HD 6770M) with the same problem.

But it's not only this, there's some general graphics related funkyness going on.

E.g., when in Aperture, some operations (like zooming in) to the image will render the main image area of the Aperture unusable until I restart the program; images there won't refresh no matter what I do, like selecting a different image in the browser, zomming in and out, etc.

In Photoshop CS6, too, some operations will carve out a section of the image (like where a dialog box was), which will never refresh after that until I restart the program.  At first I thought it was the apps not compatible with Mavericks, but now that both Photoshop and Aperture have seen updates since Manericks, and these problems persist, I'm thinking it's the OS and/or my graphics card.

There was an issue with the particular graphics card that shipped with this machine; I myself had to get it replaced several months ago.  Quite annoying I must say, as Aperture and Photoshop are pretty much all that I intensively use this machine for.

Yes close ALL APPLICATIONS before trying to Install Mavericks. You can't have applications open while trying to do system UPGRADES or UPDATES. Restart your computer and start from scratch.

This is such a relief for me to see this posted, as I am having the same problems. I've been dealing with the multi-colored squares and flashing blocks for a few months now, but they've been increasing in severity. I run Windows through Bootcamp and it is also 10x worse when I'm running Windows, to the point where I can't even use it sometimes. I can't deal with it anymore when it's interferring with getting work done. I've been considering wiping the system and reinstalling everything, but I have a feeling that won't fix the problem.

My Mac is also from 2011, 27in with 2.7 GHz Core i5 and the Radeon HD 6770M. The issue happens on both the Mac OS and Windows.

Oddly enough it was a replacement for my 2009 Mac that died; the Apple techs couldn't figure out what was wrong with my old one, even after replacing a few parts, and gave me this one as a replacement. :\ I really didn't want to go through this again only 2 years later.

Message was edited by: MerMc I should add that I'm running Mac OS X 10.6, not Mavericks, which is the new OS? I didn't even know they had announced another.

I also have the same problem under Mavericks with the same iMac and Gfx card. I've even had the computer crash hard 3 or 4 times with a GPU hang and other gfx card related crashes. This continues under 10.9.1, but the drivers haven't appeared to have been updated.

The quick way to clear the artifacts when they occur is to trigger Exposé for showing all windows for an app. The crashes seem to come after a few days of not rebooting so rebooting often may be advisable.

I've reset the PMU and NVRAM which may provide some temporary relief, but it doesn't last.

Everything was fine before Mavericks, so it seems likely that it's sofware related unless there's a widespread problem with this card that just now coincidentally coming out.

Reading other threads it seems that similar gfx cards from the same time period are having issues on Macbook Pros which they've dealt with by switching off the discrete gfx option, which we can't because it's our only gfx option.

I often work with 2 Safari windows open covering my screen and I find that the gfx glitched happen less often in that configuration.

It's all just stressful and annoying and I hope they come up with a solution soon.

I don't think there is going to be a software-based solution to this.  I'm going to be out of the country for 3 weeks starting 12/30. I'm gonna take this iMac to the Apple Store and tell them to give me a complete fix by the time I get back.

I have the same since the 10.9.1 Mavericks update.

First some very heavy funky colored flickering. Then suddenly a light gray screen, and my Mac hung.

The logs says
GPU hang:
kernel[0]: Trying restart GPU

it was so bad I had to do a hard reboot.

Then I heard the startup sound a couple of times, repeatedly.

After a few hard shutdowns (keeping the power button pressed) it rebooted again.

Gave me an awkward feeling for 5 minutes... This never happened before.

My Mac:

MacBook Pro Late 2011

OS X 10.9.1

Processor 2.2 Ghz Intel Core i7

Memory 16 GB 1333 MHz DDR 3

Graphics AMD Radeon HD 6750M 512 MB

Serial nr C02GQ17DDV7N

I'm seeing similar issues, random color blocks dotted on portions of my screen, general black flickering along lines of windows.  It started when I went to 10.9, has actually increased with 10.9.1.

I'm going to try an NVRAM reset & possibly even SMC reset.  I know in past sometimes clearing those 2 fixes it when specific to issues following an upgrade.  Overall I am loving the performance of Mavericks, hopefully Apple can find the root of this issue soon.  Wondering if it could even be a firmware update that is needed & not the OS.

I have seen the same issues with a 2010 mid year iMac now and there is a pretty long thread now of troubleshooting.  However as far as I can tell so far there is not a concrete solution to fixing the issue.  Maybe some of the troubleshooting, comments etc will be helpful?

My display looks somewhat similar to the original post but is highly variable.  Interestingly I do see a similar pattern of the square clusters.  If looking from the top of the screen downward the clusters show up in somewhat organized rows.  I also see that on mine and they are spaced out in a simliar manner.  The quantity of flashing squares per cluster seems to vary quite a bit.  I have no idea of the paragraph adds any useful information, just something I have noticed.

Here is the link to the 2010 multi-colored flashing blocks issue:

https://discussions.apple.com/message/18095126

My iMac Stats:

27-inch, iMac Mid 2010

Memory 8GB 1333 MHZ DDR3

Graphics ATI Radeon HD 5750 1024 MB

OS X 10.9.1 (13B42)

Processor 2.93 GHz Intel Core i7

I had the colored blocks problem sometime soon after upgrading to Mavericks. I was convinced it was a GPU malfunction. I took my iMac GPU out to inspect it before I contacted Apple Support (dumb move FYI). Apple Support suggested I reset the SMC and PRAM. But by this point I already had my iMac completely dissembled. The original thermal paste job on the GPU to Heat Sink contacts looked terrible. I'm not sure if it was refurbished or if Apple did it.  I cleaned and replaced the thermal paste carefully on my GPU and reinstalled it. I reset the PRAM and SMC on restarting. The blocks appeared for the first few seconds of boot but haven't returned yet. A few days of normal use have passed and still no blocks. Not sure if it was PRAM, SMC, or the Thermal Paste Job. Finger crossed I think it is fixed. A new GPU runs around $500, probably more.

My iMac Stats

27-inch iMac Mid 2010

2.93 GHz Intel Core i7

16 GB 1333 MHz DDR3

ATI Radeon HD 5750 1024 MB

OS X 10.9.1

I have just seen this for the first time on my 27" iMac.  I don't use it very often since I'm on my MBP most of the time but this is a new phenomenon and I've had Mavericks installed since it came out.  Has anyone seen any progress on this on another thread maybe?

Model Name:          iMac

  Model Identifier:          iMac12,2

  Processor Name:          Intel Core i5

  Processor Speed:          2.7 GHz

Chipset Model:          AMD Radeon HD 6770M 512MB

Yup, after going back and forth, Apple Store finally replaced my logic board and the Radeon graphics card (though it's the same 6770M), and then and only then did the blocks go away.  You need to be persistent; the issue apprently doesn't show up in any of their diagnostic tests, so take a video of what's happening, and convince the Genius that it's definitely a logic board / GPU issue.

I ended up getting the graphics card replaced at the end of December and it's been fine ever since.

Same problem here, mid 2011 27", Radeon 6770, Mavericks, etc.

The problem may be getting worse slowly and mainly appears on medium gray regions windows which have been static for a while, and is particulary strong on the external Dell monitor - typically toward the right sides of the screens. If you move the window, it stops for a while. Checked internal temps, screen saver mode, nearby cellular signal & RF sources (iPad, iPhone), second monitor connected or not.

The pattern of blinking seems to repeat: a period flickering followed by shorter period of very fast flickering, which reminds me of the sound of an audio noise problem I had when a cell phone was near my Mac. So far, the noise problem does not appear when the iPhone (T-Mobile) and iPad (Verizon) are off. The problem appears if I turn on the iPhone, however it does not go away when I turn off the phone, unless I also move or update the afflicted window (iPhoto's gray background is a good example). Only one day of experimentation with this, so it is probably premature to conclude that RF interference is a factor.

This has been going on long enough that I can't associate it with any system changes, however I've had the phone and pod for a while and I don't think it appeared when they did. If it is indeed RF related, then that leaves three possibilites: (1) I changed something, such as an OS level, and didn't associate the problem with it, (2) the RF interference is increasing or, (3) the iMac is becoming increasingly sensitive to the RF interference.

Anybody able to validate this? I'd hate to crack open my iMac and put in a new GPU only to find it wasn't the root cause!

Spoke too soon. No cell phone RF overnight but the flickering pixels are back in force.

最後更新：2017-10-03 21:45:26

  上一篇： install gtx 780m driver on imac

  下一篇： HIGH SIERRA CRASHING