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

Ken thank you for the response. I have the same machine you have and I am also running 10.7.2. I am experiencing less freezes with 10.7.2 than 10.6.8. It is good to know that I can apply the fix if I continue to run into any problems. This discussion thread has been a real help. Thank you everyone who posted helpful hints.

Hi people,

I have this freezes some time ago before Christmas, sometimes when i log in the Question Mark symbol appears, i read that my HD was dying, so i change and my Imac was faster, i really enjoy and was happy my problem was gone. It last only a week and the freezes starts again, and know my computer don't even starts?

I've run the hardware text several times and a bunch of keys combinations but with no sucess 😟

I've been reading this threat for some time, could i get some help here.

Aluminium Imac, August 2008

Imac 8.1

Intel Core Duo

3.06 GHz

CPU Cache: 6 Mb

NVIDIA 8800 GT

VRAM: 512 Mb

Memory: 4 Gb - 2x2Gb 800Mhz

Thank you so much for fixing what Apple didn't. I managed to fix my iMac 7,1 running Lion by using the 10.6.3 kext files before, my iMac was a piece of s*, it froze everytime I wanted to use it.

thanks again!!!

ricardofromfunchal wrote:

Hi people,

I have this freezes some time ago before Christmas, sometimes when i log in the Question Mark symbol appears, i read that my HD was dying, so i change and my Imac was faster, i really enjoy and was happy my problem was gone. It last only a week and the freezes starts again, and know my computer don't even starts?

I've run the hardware text several times and a bunch of keys combinations but with no sucess 😟

I've been reading this threat for some time, could i get some help here.

Aluminium Imac, August 2008

Imac 8.1

Intel Core Duo

3.06 GHz

CPU Cache: 6 Mb

NVIDIA 8800 GT

VRAM: 512 Mb

Memory: 4 Gb - 2x2Gb 800Mhz

By the way i am running the Mac OS X Leopard 10.5.8.

Anyone got an idea how i boot my Imac?

Hello. I'v got the same mac and freezing problem. The question is if this occurred before upgrading to Lion? In my case I don't remenber.

Hi, i don't think it's about Lion, because e never upgrade to Lion or even Snow Leopard.

Today i get a new HD and install the Leopard from the shipped dvd in an external disk shell, and put into my imac, and the imac don't even start, i don't know what is mu real problem here, i've run the hardware text and all seems to be fine, i've tried to enter in Safe mode, making a fsck, pram... whatever, my imac don't start 😟

The sinptoms are always the same, the Apple logo appears and the "spinning circle" and after that just freezes!

My guess is that the computer somehow don't recognize the system or maybe or there are some conflit with the graphic board.

Cheers.

Hi,

I've seen people talk about changing "kext" files, how can i do that if may imac don't even start?, can i take my HD and put it in a external shell and do that? Like to get some help 🙂

Cheers.

if you have the same freezy problem with your imac - e.g. the gpu crashes, not kernel panic - the box can be repaired if you have "remote login" (a.k.a ssh) enabled. in this case you can use any other mac/pc/ios device to start an ssh session to your cripled imac, copy the kexts over, and install them just like you would with terminal.

or you can take your old SL 10.6 dvd, make your imac boot from it, and instead of installing open up a terminal from the menu, and use an usb thumb to transfer the needed kexts.

from the top of my head i'd tell that you probably have some broken ATI kexts in your kextcache and as you try to boot normally, osx can't load them, that's why you don't have "visual contact".

you can force a kext cache rebuild by issuing this simple command in Terminal:

sudo touch /System/Library/Extensions

and then wait 4-5 minutes so the caches are rebuilt for sure.

then you can restart your mac.

Hi swmaster, thanks very much for your reply, you just give me hope in this.

I'm a simple user of apple computers and some stuff i'm quite away to understand as this problems i'm having, i don't think i have that "remote login" (ssh) enable, could i get in just connecting a firewire to another imac?

One question, how can i know wich kext files are broken and wich kexts i put in place?

Thanks a lot,

Cheers

PS. sorry for my english, it's not my mother language 😝

My 8,1 iMac (10.6.8) also started having black screens a few days ago and then would suddenly wake up. It was like this for a couple of days and I found this thread so I had hope! I did the PR and SMC suggestions but no joy. Sadly, now I have a permanent black screen.

I looked for kext files but didn't have any. This machine has an NVIDIA 8800 GS card.

I can access the iMac from a laptop and so know that the HDD is all okay. I just tried starting it up from a SL DVD and it is still black. This sounds more like a hardware problem now.

Any suggestions?

Turn on your Imac with the "D" key pressed and run a hardware text to see if that is your problem.

Cheers.

Thanks for the suggestion. At first I thought, my screen is totally black all the time, what will I see. But I did it in hope that something might happen.

At first nothing did happen. Still black screen. After I let go of the D key the computer started up normally and with the screen back! However it was flickering across a band about 1/3 the way down the screen. As the screen warmed up the flickering stopped.

I tried to start back up again with the D and same thing, nothing until I let go of the D and then a screen. So I figured I didn't have the hardware test installed. Found a DMG, installed it and tried again. Still no joy and this time no screen.

Have turned off the computer to cool it down and will see if the screen comes back. I am now pretty convinced it is a hardware problem, since the screen is flickering and faded in and out to black the second time, then was fine after warming up.

Thanks for the suggestion though. I can't get the hardware test to run as yet but will keep trying.

Update on what info I have found.

For all owners of any Mac that has a NVIDIA 8x00 graphics card (many of the 2007 and 2008 models), your problem is likely to be a GPU failure.

I have the iMac 8,1 2008 with the NVIDIA 8800 GS card, which seems to be a GPU with recurrent faults.

Go here for more info:

http://forums.macrumors.com/showthread.php?t=1085213

It would seem that Apple should know about this problem as they were part of a successful lawsuit against NVIDIA regarding their 8600 cards in MBPs.

Many iMac owners seem to be getting their GPU (and in some cases logic board) replaced for free.

Hope this info will help those with NVIDIA cards sort out their problems and not waste as much time as I did!

After more than 15 days without a freeze on my iMac, I can only say:

Thank you to everyone who made it possible to fix it !!

iMac 7.1 , 2Ghz, 2GB, ATI HD2400

SL 10.6.7 and kext from 10.6.2 (Harkaitz method)

Just thought you should now. I just got my Mac back from repair. They found that one of the RAM was defect.

Maybe it´s just as simple as that... for everyone...