Mid 2011 iMac Graphics Problems with Yosemite

As a few other here noticed: if you change a software settings, things work smoothly. How and why AMD/ATI would replace such a piece of hardware I dunno. As far as you can get someone at Apple to replace things for you, that's nice. As said: glad it worked for you.

For some others (as myself) it will be switching transparency OFF for the moment being and wait and see what happens with the first update to the OS.

I just want to point out that the solution you are suggesting only applies to a specific AMD Radeon card, not all of them. Here is the Apple support article that details the replacement program you mentioned.

iMac (27-inch): AMD Radeon 6970M Video Card Replacement Program - Apple Support

I was having this issue with my 2010 iMac with a Radeon card. I am 100% convinced after all my troubleshooting that this is a driver issue with Yosemite and older iMacs. We will just have to wait for Apple to release a software fix for this.

Patrick

And, Pat, I would agree that the card you mentioned is certainly suspect.....but, I, will point out that as I had stated, the Apple eng/tech gave me a CS Code (repair code) that was ALSO good for my Radeon 6770. Yup, 6770M 512! Under the CS code, THAT Radeon was replaced, as was the internal Super Drive. AND, almost 30 hours later, everything is running better than ever!

(He said that the code he was giving me was going to be good for whatever it took to restore my Mac to optimum condition.)

ABOUT 10.10.1

https://developer.apple.com/news/?id=11032014a

By Gregg Keizer

Apple told developers that the first update to OS Yosemite will include changes to Wi-Fi, a hopeful sign for customers who have reported that the new OS crippled their Internet connections.

Yosemite 10.10.1, which was seeded Monday to registered developers only, will include changes to the Notification Center and to Wi-Fi, according to several Apple-centric blogs, includingMacRumors. Computerworld confirmed the beta availability and its areas of focus.

Apple may be working on a fix -- or fixes -- for the Wi-Fi connection bugs that have plagued some Yosemite users since the upgrade's Oct. 16 launch.

Although Apple does not detail changes prior to publicly launching an update, the appearance of Wi-Fi on the short list may provide Yosemite users some solace if not an immediate solution.

The discussion forums on Apple's support site have continued to accumulate large numbers of messages from users who say that their Wi-Fi connections haven't worked reliably since they upgraded to OS X Yosemite.

As of late Monday, the largest thread dedicated to wireless networking problems contained more than 770 messages and had been viewed nearly 104,000 times, large numbers for Apple's peer-to-peer support.

Reports of connectivity issues cropped up within hours of Apple releasing Yosemite on Oct. 16, and have continued to pour in since.

"I am a Cisco- and Unix-qualified software engineer and have tried every trick in the book since Yosemite's release and I don't think I'm going to find a easy solution as I think this is a serious hardware-software conflict," said kevinski_uk in a Nov. 3 message. "Apple have basically rendered my [MacBook Pro] useless unless I downgrade to 10.9.3."

Some users have had success implementing one or more of the seemingly endless suggestions that have piled up on that thread, others on Apple's support site and on third-party blogs. Turning Bluetooth off on nearby Macs and iOS devices has worked for some, for example, but not for all. Others reported having Wi-Fi connectivity problems with OS X Mavericks as well, but that conditions sharply deteriorated once Yosemite had been installed.

"Tried everything in the book ... many things seem to provide a temporary respite, which is even more peculiar," said OceanDrifter.

Those who had contacted Apple support have reported that they've provided system and connectivity data to the company's engineers, with some concluding that meant Apple was working on a fix.

But Apple's secrecy -- it rarely acknowledges bugs or discusses fixes-in-progress -- has infuriated many. "Honestly, they need to start by admitting there's an issue. It's seriously upsetting that they have said nothing!" asserted janiceva.

Among Computerworld staffers who ran Yosemite developer previews prior to the launch, some encountered no Wi-Fi problems while others had serious issues through the first several iterations of the summer's beta, with Wi-Fi connectivity becoming stable late in the preview process and remaining so with the final code.

It's impossible to predict when Apple will release Yosemite 10.10.1 to the public, as the company declines to disclose dates. The first update to 2013's Mavericks appeared eight weeks after the operating system's debut; in 2012, Apple shipped the first update to Mountain Lion four weeks after that edition's release.

I upgraded from Mavericks last night to 10.10 on my Mid 2011, 27-inch iMac with AMD Radeon 6970M, 2048 MB.

I have 2 thunderbolt-adapter secondary displays at 1920x1080 each.

So far I've experienced no display issues.

EXACT SAME PROBLEM WITH 27' MID 2010 IMAC. HAD THE SAME PROBLEM LAST YEAR WITH MAVERICKS, AND TOOK OVER 2 MONTHS TO GET FIXED WITH SOFTWARE UPDATES.

Imac 2010 graphics problem: Generic RGB was my (so far) temporary saviour.

Quick facts:

- Updated to Yosemite and was able to work for a day or so (photographer).
Some photoshop tools run very slow! - Computer is very slow on start up - expected after upgrade, but still annoying.

- Upgraded Java runtime (but not sure problems are related, might just have been the restart?)

- After this my Imac started acting very weird, displaying all the problems mentioned above: - artefacts on screen, weird freezes, and so on.

The solution (for me).

Someone else posted this simple temporary bug fix - and it worked for me - Im now able to work again! VERY NICE!! Just wanted to share.

Go into Screen adjustments - change BG color to a solid color (not sure why) - and then change your screen color adjustment to "generic RGB". Disc

Run "Disc Utilities" to repair disk, just in case you haven't after update.

Restart.

I did this - and now I can work on my computer - some photoshop tools are acting very weird (can't use lassoe tool... pretty big problem, but I manage). But besides from that - computer is functioning now (48 hours) - with no freezes, and no artefacts.

NOTE - I had to use Quicksilver / Spotlight to even get into system adjustments - just a hint if your machine is that bad 🙂

NOTE 2 - colors are not quite as vivid - recalibration is needed if you do print work (just another reminder).

OMG!!!! TOTALLY WORKED!!!!! THNX

Was constantly freezing and displaying weird boxes on screen etc... And as soon as i installed latest Java and restarted, it has magically healed.

Dont know what Java has to do woth the graphics card. but Thumbs up.

https://java.com/en/download/mac_download.jsp?locale=en

I think my problem came AFTER installed Java - but I might actually have gotten the wrong update (not specifically for Apple).

Not sure - there could be some relation.

I tried rolling back to normal setting after I restarted a few times with Java - and now I have no problems - though still some problems in photoshop, with lassoe tool!?

Anyway glad you found a solution!

This didn't work for me. The only solution for my mid 2011 27" iMac was turning Transparency OFF. I have been working totally fine without any display issue for about 5 days only after turning transparency OFF. As soon I turn transparency ON the issue is back in less than 2 min.

Yea I guess none of us has the correct answer to the problem - but nice that people add different solutions to get a computer that works... at least until (hopefully) theres a fix of what is really causing the problem.

For my 27" Mid 2010 iMac, I had to turn off Transparency AND upgrade the Java runtime to the latest version (as of this writing, 7 update 71). After several hours, no longer do I see random blocks of pixels nor has the GUI locked up. Otherwise, random blocks would occur within a minute. We'll see how long this lasts...

So, 24 hours after i installed Java, i only got the random blocks once when trying to view a video. So thats a great imporvment because before it was constantly doing it. Also turned off transpreancy, and hasnt done it at all. Mac is also stable now.

Thanks to everyone in this thread. I found a solution to my problems: turning off transparency in the Accessibility preference pane.

My system: mid-2011 iMac 21.5 inch with Radeon 6770 graphics. Also, home-rolled Fusion drive.

After I installed Yosemite, the green/red glitches that I regularly had with Mavericks came back in force, sometimes getting so bad that the screen was unreadable. So I tried swapping out the AMD6000controller.kext as suggested by someone near the top of this thread. It worked great for about 8 hours. Then my system crashed and wouldn't reboot. It got stuck in a loop when booting: would get up to 1/3 startup, then have a kernel panic. The system was completely unusable.

After a couple of clean installs (and a few anxiety-filled and intensely frustrating days), I turned off transparency. Problem solved. My system boots, is stable. Occasionally, I get a few green/red blocks flash. I just force the screen to redraw that window (say, by swapping spaces, then swapping back again).

I was in deep despair until I tried reducing transparency. Thanks to everyone who suggested it.

Also install latest Java. Thats makes its completely stop doing the grenn red flashes.