24" iMac Screen Freezes since 10.6.3 update - pls help!

I'm trying to decide whether it's worth my while to try and use my AppleCare to replace the GPU on my iMac 8,1 running under OS X 10.6.8. Since I did the kext fix about six months ago, I haven't had any freezes. Prior to that, I had numerous random freezes which I reported to Apple with no resolution.

I'm concerned about whether the kext fix will continue to work going forward especially if I choose to upgrade to Lion or Mountain Lion. I've got to make the decision soon because my AppleCare expires at the end of this month but I don't want to waste my time if I'm just going to get shot down by Apple.

Isn't your apple care over now? Your iMac is first quarter 2008, it's first quarter 2012 now, that's 4 years ago. Isn't apple care only for 3 years?

Well, if you can get a new GPU for free, I'd say do it. Mine still works great without the kext fix.

As someone who's applied the kext fix up to Lion (10.7.3), on an iMac 7,1 I can tell you it works just fine at least that far. 10.7.3 supposedly had some fixes for older ATI cards, which my imac has, but it didn't help. You can upgrade that far without a problem. I imagine, I'll be able to ride Lion as far as it will go at this point. Mountain Lion is another story, but I'm hopefull, it will work on it too.

@Fritos_Chips:I bought it as a refurb from Apple in March 2009.

@TK111: Any tips on what to say to get Apple to replace the GPU?

I had gotten upset about all the freezes, so I started documenting each time it happened for about six months. It was, as you probably know, several times a week, sometimes several times a day. That seemed to sway their decision. Not much help if you haven't done that, but just my experience.

TK111 wrote:

You're right. The kext fixes worked for me, but I also got a new GPU (ATI 2600 Pro) under Apple Care 9 months ago and haven't had a problem since then even with the new kexts. Yippee! The cost would have been $179 for the GPU otherwise.

Where do you get the GPU for $179? Couldn't find anything below $268 …

I got it under AppleCare, fixed at the Apple Store. $179 was what it said on the receipt, but I suppose labor would have been on top of that if I'd had to pay for it. Don't know about prices on the open market.

CW3X, I also have an iMac 8,1 running 10.6.8 in 64-bit mode with the kext fix (which has been working well). From what I've seen reported, I'm resonably confident of the kext fix working through all the Lion releases, and maybe Mountain Lion, too.

Having said that, if mine were still under AppleCare, I would seek out a replacement GPU. Partly for the Mountain Lion uncertainty, and more because I might want to sell the machine someday. Can you imagine saying to a potential buyer "Well, after each OS X release, you'll have to copy these old system kernel extension files over, and...?" Kinda detracts from the "It just works" idea.

While it was still under AppleCare, I took my iMac in for service on 3 different occasions, and since they couldn't reproduce the problem during their hardware test they said I was out of luck. I also have talked with Apple support on the phone multiple times and after they said they would get back to me, but they never did.

This is exactly my problem -- I would like to sell my iMac and upgrade, but I feel I can't without getting this problem fixed first. It appears that whether the GPU gets switched out or not under AppleCare is a random result based on how the service employee feels. I'm debating trying to take the computer to an Apple Store, update the computer in front of them so that the kext files get overwritten, and then working at the store until it freezes. Or suing Apple in small claims court...

I finally got the time to take a picture and post

I've now down graded all the way to Leopard. I'll just stick with this old OS until someone posts that Apple has fixed our issue.

I tried Windows 8 recently. That alternative isn't looking too good either. I might just go back to Windows 7 altogether...

Since i installed Lion (went from leopard to lion) my iMac 8,1 early 2008 Ati 2600 HD has the same problem as described here.

It started with the black or green screen with lines crash. After upgrading to 10.7.3 it started to freeze (could only move the mouse).

The solution to this problem was to install the 10.7.3 combo update (it puts a "d" after the serial number when correct installed) But now the black or green screen with lines crash is back:(

anyone tried the old kext files fix on 10.7.3 with the combo update?

I also found this solution

http://blog.djmnet.org/2011/02/03/snow-leopard-crashes-on-a-24-imac/

"Apparently Snow Leopard drives the GPU harder than Leopard does, but runs the iMac’s fans at the same barely-audible speeds. The problem is more likely to occur on iMacs that are left on all the time, as mine is."

did not tried this yet...

I stated in this thread some time ago about 'Fan Control for Mac'. It worked for me to a point. By cooling down the GPU I reduced the number of times my computer would act up. But it did NOT totally eliminate the problem. I had my GPU replaced 3 weeks ago under APPLE CARE. No more freeze ups. The GPU that I had replaced was the GeForce GT 130 by NVIDIA. This must have been a revised card as it was the same model as I had when I purchased my computer. Since the card was replaced I turned my fan speeds back down and have not had any problems. I am able to multitask graphics driven apps with ease.