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

I actually partitioned my HD and kept Snow Leopard on one and ML on the other. (I had replaced my hard drive with a 1000 G because it was on its way out)

With ML you lose Rosetta Stone forever so it won't run Palm desktop, Clarisworks, and a few other old favorite programs. That's why I kept the snow leopard install. I haven't gone back to it much but it's nice to know it's there.

On the install, I went from the original install disks (10.4?), then upgraded to SL, then ML.

I have the Kext fix installed but it's not improving performance on my 8,1 iMac with the HD 2400 card. My slowdowns tend to happen every afternoon specifically after graphic-intensive screen sharing sessions with customers. Of course, a simple reboot fixes it for a while.

Like many others, mine has been in the Apple Store twice. Once because we thought it might be the hard disk (which it wasn't) and the other time they kept it overnight to see if they could experience issues and run tests. Nothing was ever found.

Does anyone have any other suggestions?

I don't remember anything in this thread about slowdowns. The kext fix is for dead freezes that require a hard shutdown.

hi

i have imac 12.2 , mid 2011 with 6970M graphic

i have exactly this problem, my mac suddenly stop working and the screen becomes like the image posted in first post

it happens both in mac os and windows, can anyone help me how to fix it?

I had the same issue, and I Have watch this thread for long time now. The screen of the iMac 8,1 (with nvidia) freese and the only solution then was a hard reset. Like more of you I was assuming that the this was a software issue. Afew weeks ago I removed one of the ram modules and the freesing became more present, more often. When I switched the two ram modules (2 mb each) the problem was over. I have used the iMac for weeks without any freezing. A few days ago I have ordered new ram modules and istalled them and, until now, no new freeses!

SoI think this issue has something to do with "wrong" ram modules.

Hoopfully this is helpful for some of you.

It's not wrong RAM modules, as it's unlikely that all of us got wrong modules.  It's the kext issue that has been documented here over the past couple of years.  Since installing the kext fix, I (and many others here) have had no freezes.

is there any kext fix for ati 6970M?

has anyone tried this to fix the problem? http://support.apple.com/kb/DL1444?viewlocale=en_US&locale=en_US

Yes. And it had not worked unlike the KEXT...

I also have a 2007 intel core imac and since upgrading to Snow Leopard 10.6.3 I'm having random freezes. It can happen anytime, especially after waking from sleep mode and the only way out is to turn the computer off and on. Sometimes I get a dark blue screen, sometimes grey. This is getting very frustrating - I upgraded to improve my computer, not to get all this hassle! From reading this and similar threads, I gather it is a problem that Apple need to resolve -anyone got any ideas in the meantime?

This is a problem that's been around since 10.6.3 was released. Apple has never done anything about it, so don't expect them to do anything about it. There's been a lot of ranting on this thread, but Apple has not bothered to deal with it.

But never fear, the kext fix mentioned in this thread works amazingly well for your machine. I have an iMac identical to yours. I've upgraded it to the latest version of Mountain Lion, 10.8.2, and the kext fix has been rock solid throughout. After I applied the kext fix, my machine has NEVER frozen. It's run like you expect an Apple computer to run.

Guys the link for the download is down. We can't get acces to Kext Helper B7! Please help!

@DataRusty

http://blog.krzysztof-turek.com/wp-content/uploads/2012/10/Kext-Helper-b7.zip

Just jumping on this as my 2007 24" iMac has started to freeze and "GPU Debug Info End" with a load of kernel[0] entries are newcomers to the system log.  Have noticed the whole GPU area has started to get hot (60ºC) and warm up with literally no activity.  Can't see GPU activity as it seems to have been blocked from the 3rd-party monitors in 10.8

And if the problem was linked to the kexts inducing hardware problem, because of the controller heating more for example ?

Look at this : #451: someone managed to repair an Apple motherboard by resoldering a BGA (Ball grid array) chip.

Somebody feels like trying this ?

My iMac 8,1 with the ATi 2600 has exhibited very exactly the symptom described here some years ago but inexplicably healed himself after five or six crashes. Today I'm using the stock kext that are loaded with ML 10.8.2. As an electronician, it makes me believe that is hardware related (but software induced).