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

TK111: Thank you! Do I understand you right, that the trouble-free one (the replacement) has 113-B2250L-259 as “ROM Version”?

Yes, that's right, Tardigrada.

Hi, here it is:

ROM Revision: 113-B2250A-207 for an ATI, RadeonHD2400 and I have a 21".

About safe mode and 10.6.8 with kext I can’t tell, I was advised here that the kext fix would not work for that version because of the change from 32bit to 64bit as my 7,1 cannot boot into 64bit, I guess most people jumped from 10.6.7 directly to Lion.

https://discussions.apple.com/thread/2384136?answerId=18735660022#18735660022&ac_cid=tw123456#18735660

Guess I spoke too soon. After a trouble free experience with my new GPU (as spoken about above) for the whole time I had Lion, I have had four freeze-ups requiring a hard shutdown and restart since I installed Mountain Lion. One a day for the last three days. This is disappointing, but I know we have much more direct words for it. If it keeps up I guess I'll have to use the kext fix and thank goodness for that, but ****.

Alright, here is my personal experience.

This issue is really annoying. It's been two years and… well… no solution on Apple's side. If you are using your iMac all day, you should know how annoying it is, especially as this thread is growing… Growing.

So, before using this "kext tip" — found it a year ago but I'm not über comfortable with modifying kernel extensions so I decided to make it my "last resort" or pis-aller —, I tried several things: Clean Install, Firmware update […] using SMC Fan Control.

As far as I am concerned, using SMC Fan Control to keep my iMac (v8.1) below 40°C (104F) had been working quite well. I may tell the number of freezes was divided by three.

I tried that since I noticed my iMac was quite OK during Winter (1 or 2 freezes - 4 months) but it froze a lot during summer (up to five freezes a day). It was quite surprising since my job doesn't imply graphics-heavy tasks.

Don't know if that can help. But I think it is something noteworthy so…

Using 10.6.2 kext, it just works flawlessly. Still running SMC Fan Control. 1 week later, no freeze at all.

It may also be interesting to tell I know people with the same problem who actually opened their iMac in order to clean inside. Guess what? There was a **** of a lot of dust in there. And once they got rid of all this dust, their iMac was running a lot cooler and the number of freezes they encountered was divided as well.

To sum things up : iMac now working as it should, fingers crossed.

@JayPan.

It certainly seemed to be the case that overheating was part of the problem. Whether that is mitigated by software fix (i.e. kext files/drivers) or a replacement graphic card hardware, the end result might be the same.

As an independant Apple Hardware tech, this problem has been a thorn in my side for a long time, not the least because my wife has this iMac.

I had considered it an overheating issue early on because of the desk nook where my wife was using the machine and because it seemed to happen when graphic intensive tasks were at work. This might be the reason that so many on this thread thought it had to do with Flash.

I don't doubt that there is an overheating issue, but the question has been how to mitigate it. Either the software fix (kext files/drivers) seem to do it or replacing the hardware. So, in effect, the overheating is the symptom, not the cause.

If overheating is the answer, then why can my affected Mac run Windows 7, and sustain running 3DMark with the GPU reaching 60C and not crash?

Also, I've had the iMac lock up pretty quick with it's temperature only around 32c according to smcFanControl.

As I've said before, there were certain ATI drivers on Windows which caused more or less the same problem - on Windows the display subsystem can detect a freeze and reinitialise the hardware. This happened frequently at one stage with these drivers. ATI corrected the problem in later driver revisions, which my girlfriend is using on the affected iMac with no problems at all.

It is solely a software issue - Apple have probably brought in the same problem with some code they got from ATI, and simply cannot be bothered to correct the problem.

@JayPan, @CJH_Canada

Hi can anyone here advise me on what would be the correct RPM to use with SMC Fan Control, for my imac model? I am running a iMac7,1 aluminium 20”. I want to try it.

Although I am sure it is a software problem with a drive of the ATI, something very similar happened with Leopard and ATI in 2007 (you may read link below )...

Read more: http://www.macnn.com/articles/07/10/04/imac.freezing.redux/#ixzz23O17W6Yv

“ A company spokesperson told the publication that “A small number of iMac users have made us aware that a recent software update issued by Apple can sometimes cause their iMacs to freeze(...)

Apple technical support has already confirmed the issue with several users, according to the threads, and the problem reportedly has been narrowed to the ATI Radeon HD cards inside the iMac. However, only some owners are reporting more crashes with graphics-intensive programs (e.g. games), while the rest say it is random or connected to extended periods of use. ”

--------------------------------------------------------------------

...But, I have to say that I’m having a very hot summer here and since temperatures raised my freezes started happening more frequently. My computer was all cleaned inside last December. No hardware issues but it is true that my TechTools acuses always a slight divergence with temperature.

This is what I have now:

ODD— 999rpm

HDD— 1200rpm

CPU— 1200rpm

With iStat Nano I am detecting for temperatures (at night):

HD - 80.6F / 27ºC

CPU A - 89.6F / 32ºC

GPU - 95F / 35ºC

GPU diode - 96.8 /36ºC

GPU Heatsink - 93.2F / 34ºC

Ambient - 71,6F / 22ºC

memory controller - 89.6F / 32ºC

thanks 🙂

OK, it seems I was not able to make me understood — not sure if that's proper english but you get the idea 😕.

I am not saying overheating is the answer. It is not since I still had quite a lot of freezes while keeping my iMac below 40°C… which is not overheating at all to me.

What I am saying is I tried and used this and it improved my personal situation dramatically. And it helped some of my friend's too. Not all of my friends eventually.

For some reason, unplugging my printer helped too. But I won't say USB or printer's drivers are the answer. It is not.

Obviously, as anyone can tell, using 10.6.2 kext is the only solution. But I thought I could share my experience, which is something very strange.

For example, using the latest version of Sparrow, which is not graphic intensive, triggered five freezes in just 4 hours. That is why I finally applied 10.6.2 kext. Using Mail, I had a lot less freezes. Is Sparrow the answer? It is not. But I think you can agree this is very strange. As a matter of fact, it seems my freezes are not related to graphic intensive tasks at all.

I am just saying I used SMC Fan Control to keep my iMac below 40°C and that helped me. But just imagine using an iMac with ODD Fan running at 2800rpm, HDD fan at 3000rpm and CPU fan at 2400rpm. That's insane.

Now, if you want more oddities, I can give you.

1 - very few freezes at ≤ 40°C

2 - a little more freezes at 41 + 42°C

3 - a lot of freezes at 43 + 44 + 45°C

4 - about the same number of freezes as 2 while iMac running between 46 and 48°C (which surprised me)

So, basically, it means I could predict when freezes will happen and that's it. That took "random" out of my equation. Once again, that did not fix the issue.

Moreover, it seems some programs I use are likely to trigger freezes :

- Apple Pages

- Sparrow (latest version)

Freezes would typically multiply while running those two programs. Using photo editing software or playing games made no difference. Freezes would happen after no less than 50 youtube videos were played (playlists).

Unlike others, it looks like my freezes are not that much related to graphic intensive taks. As quoted by CarlaBlue, Apple says there are two categories : users running graphic-intensive programs and others. So just count me in the latter. That is all. But it was a less random than expected since I could predict when my iMac would freeze judging by its temp and the programs I was using. Can I explain that? I just can't. But again I thought it was useful to share this — perhaps others have had the same experience…

Hi JayPan

I understand you. It is about controlling and previewing when freezes will happen.

I want to try the SMC Fan Control because it is something I didn’t.

I read before many used it to control the issue — others advised not use it much, so I am just checking how to run the right rpm numbers.

I managed to control my freezes with “caffeine” to avoid my mac from entering sleep because “Sleep” affects me and I don’t know why. When my mac comes back from sleep I am sure to get a freeze in the next half an hour.

But I did notice they increased in Summer, mainly on days with high temperatures. I had them from 9 in 9 days, now they are happening everyday.

I work all day on the computer.

Like you I also have freezes when not using GPU intensive programs, I had it with Mail or just by staring at the browser. Or just logging in and that was when a friend of mine told me it was a faulty drive for sure... lagging...it is completely random.

But I also have guaranteed freezes, blue screens, stripes etc...when pulling on GPU if I use hardware acceleration.

Mainly with Adobe PS and Firefox with hardware acceleration on.

I also admit that prior to cleaning my fans and the insides of my mac I was having freezes every 20 minutes and my fans were really dusty.

It improved time span between crashes but the problem continued randomly.

As Apple will not fix this like in 2007, I am open to try all suggestions to keep it under control until the first release of updates for ML so as I can apply the kext. fix...

Personally, I wouldn't bother with SMC Fan Control. I tried it and my machine still froze. The only true solution is using the old 10.6.2 drivers. With those drivers in place, my machine has *never* froze. I've been running old drivers for about a year now and am currently on Mountain Lion. Currently, my machine (iMac 7,1) has been up and running for 14 days straight (since I installed Mountain Lion):

$ uptime

10:08 up 14 days, 1 hr, 4 users, load averages: 1.17 1.00 0.76

Hi Richard.

I am going to do that, I have no doubt about applying the kext. fix to solve the issue.

But I am still running snow leopard 10.6.8., when I got to this thread it was to late to apply it.

I’m one of the 60% mac users who passed Lion and never got a chance to upgrade as Apple came so fast with ML.

I have this personal method of always waiting for a while before installing a new OS so as to give Apple time to correct bugs (even like this it did not work or I would not be here), to give Adobe time to keep up because they’re always slow on keeping up and also I need to keep checking roaringapps.com to see if the apps I use are all compatible, tested and working for ML and some still aren’t.

I am just trying to keep it stable, because I can’t risk another bug on top of this one and more hours of troubleshooting are a frightening thought.

@CarlaBlue, did you consider downgrading to 10.6.7? I did that for a while because when I upgraded to 10.6.8 the kext fix wouldn't work with my machine either.

Hi fellow sufferers, My update - My Lion updates all worked with the kext fix. Moved to Mountain Lion and did the clean install as the guru suggested. I had one freeze (black screen) with nothing registering on the Console after a couple of hours. However, I ignored that and I am now some 8 days without a freeze on this session, and a week or two trouble free use before that - I just did a shutdown whilst away).

…only issue is witht he clean install, is that my purchase of Moutnain Lion does not appear on my App Store account!? But no bother.

Simon

Hi,

I just have 2 freeze in a row... But - what is very strange - after reboot my bluetooth stop working. After another reboot everything goes back to normal.

And everything is start after instaling Evernote - when I use it screen freezes....

Now I'm back to 10.6.2 kext.