Mid 2011 iMac Graphics Problems with Yosemite

Yes, Apple removed it from Apple Store the day after they released Yosemite but it should be in your App Store "Purchases". Just press Download and it will start downloading. I do recommend you to do a clean install of Mavericks with a bootable USB drive, though.

Yes.

I did an command+alt+r for internet recovery and get a gray screen for quite a while, then I reboot, I could login to the system!

Then I did reduce transparency, so far it's fine. Would try re-install mavericks if this problem happen again.

Hi guys,

In my case transparency is the trigger. As soon I turn ON transparency in my iMac the display issue is back. It takes no more than 2 min to get the display issue after transparency is ON. Then if I turn it OFF the issue is gone. This is a definitely a software glitch!!!

Hi there everyone,

same here. After turning off transparency all graphical glitches vanished.

I'm keeping it this way now and will report back to customer support.

Cheers

Günther

Had the same problem on my iMac (21.5-inch, Mid 2011) since upgrading to Yosmite. Colour squares all the time, sometimes needing a hard reset.

So far:

1. Have done a clean partition and install of Yosmite - this has NOT resolved the problem. Seemed fine a first, then colour squares appeared again.

2. Turned off transparency - I'm still getting colour squares. Not crashed yet - so could be a slight workaround the issue.

I believe this problem very much depends on the applications you have installed and their demand/use of the graphics chip.

Hope Apple is able to release a patch soon to fix 😟

Happened to me today again! After reboot, works fine so far!

Mine has been working fine since I turned OFF transparency. Not a single display issue for the las 48H.... Knock on wood 🙂

I had this happen to my 27in Mid 2011 2 days ago after Adobe Flash update came in. This morning no video on any website could be played and then kernal panics all over to the point of the machine shutting down by itself. tried to reinstall previous Flash, but that was not successful. So I pulled out a SSD drive with Yosemite installed from 3 weeks ago, and that worked with no issues, videos on youtube played, no apparent hardware issues, it was like the issue vanished. Booted back up with the version of Yosemite that was updated with the latest Adobe flash, and kernel panics and shut down happened again. Just reinstalled Yosemite, and everything booted up fine, was prompted to update FLASH and flagged it to not ask me again.

4 hours later and not a single issue in sight. Converted several videos and the graphic issue seems to have vanished. I dont know if flash was the caused of the issue, but I found that by not updating it, the issues I had went away after the reinstall of Yosemite.

Hmm, good luck for you 🙂

I still encounter blue screen, flashing screen issue etc....cannot tolerate it anymore, re-installing Mavericks.

enricoclaudio, so far I do confirm your experience. After disabling transparency I have not seen any graphical glitches for at least 48 hours.

Some overlays (brightness, volume et.al.) do get ugly square black angles with transparency turned off.

But that's better than freezing the system every few hours.

A corrective update with 10.10.1 would be welcome either way... 😉

Long story short: after wrestling with Yosemite for about 10 days I had to go back to 10.9.5 via Time Machine Recovery.

Believe me, I tried every trouble shooting step known to man before giving up on Yosemite 🙂

I run Logic Pro X a lot with hundreds of third party plugins.

With Yosemite the increased cpu load was unbelievable, Logic was unusable.

The point is, I have a mid 2011 iMac 27inch with an AMD Radeon 6970M 1024MB and I'm sure that is part of the problem.

Having returned to 10.9.5 everything is absolutely back to normal.

Thanks god for Time Machine.

Following on from my last post - since turning transparency off things seem to be running ok. I suspect still that certain applications might still cause the problem?

Hi there... the "transparency factor" has worked well enough for me. I have turned off (completely uninstalled) Adobe Flash as this was something that has always been a hassle (maybe some of you remember Steve Jobs years ago saying he doesn't want Adobe Flash on iPhones since it is the cause of a majority of crashes on Mac OS).

It could be that interacting with transparency and the ATI graphics driver. Anyway what I did was: (1) uninstall Adobe Flash using Adobe's uninstaller, (2) reboot, (3) enable transparency again. So far everything is fine, but I'd rather go for another 2 days with this before saying this is a workable solution (since I don't really need Flash, it would be more acceptable to me than the ugly side-effects when transparency is off).

I found an article at gizmodo, relative to the performance of Yosemite. Read it here -> fieldguide.gizmodo.com/the-worst-bugs-in-os-x-yosemite-and-how-to-fix-them-16526 90924
Talks about fixes for graphics, etc.