OSX Lion + 2011 iMac 27'' + Video = Freeze

I managed to fix mine.. Popped the 5750 out of the machine.. removed heatsink, and frame, and cleaned off all thermal paste.. Put it in the oven, and "baked" for 10 minutes at 200c, and let i t cool down for 30 minutes.. Reapplied thermal paste and reassembled it. no more red green and blue dots.. no lockups.. Min was totaly unusable before this.. Now it´s working 100%.. I´m pretty sure its related to the BGA soldiering on the ATI chip..

http://lifehacker.com/5823227/save-dying-video-cards-with-a-quick-bake-in-the-ov en

I believe the problem is that too, on graphics board soldering.

Like the problem on PS3, YLOD, "Yellow Light Of Death", that have the similar fix procedure.

But i 'm afraid to open it...

Thanks anyway. The right way would be Apple to recall it for a new one.

Is a design problem...

🙂

I decided to try this on my imac today. Its all back together and I was able to use it for 30 minutes with no problems before I had to go to work. I'll let you all know how it holds up over the next few days.

Mine is still working perfect.. It´s been constantly turned on since i put it together, and not a glitch yet.. I´m a little surprised that some of you says that apple replaced the video card, but the problem was still present.. This can´t be the same problem.. My card worked almost perfect if i ran my machine in safe mode, or windows 7 without the ATI driver installed.. The second i installed the driver/booted normal mode, the machine went crazy. So no doubt that the problem was related the the graphics card. If the problem comes back, i´ll just replace it with the cheapest one available.. Only use it for interweb and RDP...

I do believe the problem is on video board. Mine is. I will try that safe mode with off drivers, but for my knowledge, is the video.

And the problem here is worst on it cool. When i keep insisting, using it hard on After Effects and Maya, it get better and better, but don't stop 100% of the problems. Just keep usable.

But because it is my only work machine, i can't do that try, only if it stop working 100%.

And if i put it on Apple to change video, i would probably put the best video board i can fit in, and pay for it. Because this 500mb video board isn't felling my needs...

🙂

I was fighting with my iMac until last week, when the only thing i could try was installing Yosemite Developer update (now on number 4)

The Yosemite could manage better the machine, but the squares and locks on machine wouldn't stop, but minimize.

Observing the machine, i could see that it freeze more when cool then when in heavy use. Everyday i start to use it, it lock some times, even moving a window on screen, then, after some warm up, it turn into usable.

So, today i try something different and unusual.

I put a mp4 video (720p one, with around 150mb) into loop playback. so, the GPU never goes unused 100%. (never could down enough)

And it works. No more square dots, no more lock on, until now.

The thing i think is the problem, is a bad manufacture and a soldering problem, so, when it is cold, the parts retracts and this soldering get with contacts problem. But when it is hot, the things expand because, and then this bad soldering keep connected.

Until i have a new machine, and then i can put this one to recall/change to another new video board, this will solve my problem.

I hope that could help you all.

Cheers

I've been dealing with this issue for almost two years. At first it started with small artifacts on the screen small multicolored squares. The progressed. In this time, after Apple replacing the GPU twice and the logic board once, replacing the RAM, i was still having trouble. In fact, it was so bad that i couldn't get a minute past logging in before the system would lock up. So Apple offered me all the money i had spent at that point to try to repair my iMac returned to me towards the purchase of a new one. So I bit the bullet and ordered a new 27 iMac. I wasn't sure what to do with my old iMac. At first i thought about letting Apple recycle it for me. But then i thought there's nothing wrong with the LCD so i put it in to Target Display Mode and used it as a second monitor (with a Thunderbolt to Mini-DVI cable). It worked great! But now that i had the new one i still struggled with the fact i was able to access my data (via sharing) and use the iMac as a monitor. It was really bugging me that i had this perfectly good iMac next to me being used as a monitor!! So I decide what the heck.

I spent a few hours today reflowing the graphics card on the old iMac. I used a heat gun and replaced the thermal compound on the GPU. So i turned it on about 18 hours ago and has been on nonstop with sleep/screensavre enabled and i've not had any artifacts or freezing at all. It's like nothing was ever wrong with it.

I can only sumise/guess that Apple is replacing the Graphics cards with refurbished/old cards? I don't know for certain but the thermal compound that i cleaned off the card was dried and cracked badly.

So long story short.... a reflow and replacement of the thermal compounds seems to have done the trick! If you've got nothing else to lose give it a shot! I'm not certain if it will last or for how long but it's working now..... and i have an extra 27' iMac. =/

I also have a mid-2010 iMac i7 with the Radeon 5750 GPU. I get flashing psychedelic colored areas that cover most of the screen. We have had this since we bought it new from the local Apple store. Hard drive was replaced under warranty. Will take it in to Apple store, and ask about free replacement of the GPU. When it starts "flashing" it's pretty annoying.

After skipping Mountain Lion, I thought I would give Yosemite a go on my 27-inch Late 2009 iMac, (AMD) ATI Radeon HD 4850 512 MB, 8GB RAM.

The hope was that perhaps updated graphics drivers might fix the issue, but alas, it came up with a white screen, and after booting into safe mode the GPU errors were back in the logs.

For my card, I removed AMDRadeonX* ATIRadeonX* AMDRadeonV* kexts and Driver.bundles from /System/Library/Extensions, leaving the AMD4800Controller.kext and rebooted. At least my system came back up, but the initial load, and the login window were extremely slow.

Once up and running, the Chrome browser had continuous page repaints and was basically unusable, and my info.plist hacked version of Skype 5.1.60.947 would not even run. I was also getting a lot of random page repaints in finder windows, they may have been related to mouseovers. I did find reverting to google-chrome-34-0-1847-116 was workable, but no Skype version would allow an image from my iSight to display. I fritzed around with it for a few days, but in the end, gave up and went back to my trusty 10.7.5 Lion. Apart from the other issues, what was the point of upgrading? Also don't like using App Store for software updates, and the stupid stock notifications don't recognise mutual fund symbols.

My iMac is now 5 years old, it originally cost AUD$2,500, and it looks like Apple will never do a recall for this graphics card. I really don't have the money to upgrade, but if I ever did I would probably get a Mac mini i5 16GB RAM and a good 27-inch monitor, maybe AUD$1,500 all up. Wonder if I can use this POS as a monitor?

This is basically a poorly designed unit, the way the logic board, gpu, cpu are all jammed in together with bad solder and no proper ventilation. BTW there was a recent update to SMC FanControl, can't see a lot of difference....

My problems came back with a vengeance after tweaking the power settings via BootCamp. I eventually proved that when the GPU was hot (put under load running Heaven for a while), the problems would disappear. When cold, they were pronounced. I finally made a Genius Bar appointment and the tech agreed it was likely the GPU. To my surprise, replacing it with a factory original GPU was less than $300, labor included! That was less than the best price for the parts I could find online, and I did not want to risk breaking something opening the iMac. If you are having this problem, and you still want to get a couple more years out of your iMac, get it into the Apple Store for a new GPU before they stop stocking these parts (they maintain parts stock for 5 years, so this might not be an option by the end of 2015)!

After about 3 years of blockade I solved by replacing the video card.