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We'll just agree to disagree. What I have done works for my mid 2007 iMac and may work others who have not been able to get rid of the freezes even with the 10.6.2 kext.

A 32-bit EFI Mac cannot run a 64-bit stock Apple kernel. That's basic Mac 101. Don't forget, it was within this thread that I pioneered the kext replacement procedure and identified what kexts to replace. And I take it by your just quoting that part of my post that you concede in the argument that the iMac does indeed have a 64-bit EFI.
 
I disagree the mid 2007 iMac does have a 32-bit EFI that boots the kernel in 64-bit. If we can agree that is disagree with you. And if I am wrong than still telling the EFI to boot a 64-bit kernel has worked and worked flawlessly. Do you have a mid 2007 iMac running 10.9.5 Flawlessly? And Krysztof Turek found the solution 1/10/11 before this thread was even started in 10/25/11.
 
I disagree the mid 2007 iMac does have a 32-bit EFI that boots the kernel in 64-bit. If we can agree that is disagree with you. And if I am wrong than still telling the EFI to boot a 64-bit kernel has worked and worked flawlessly. Do you have a mid 2007 iMac running 10.9.5 Flawlessly? And Krysztof Turek found the solution 1/10/11 before this thread was even started in 10/25/11.

Yes I have a 2007 iMac running very well. This particular one isn't affected by the freezing issue. I do have many others that are. While this thread wasn't created until a later date, I did personally spearhead the fix in many other areas. Going by your continued indifference for correct information, you have not ran the provided Terminal command to personally verify the bit count of the EFI on your iMac. Either that or you don't have a 2007 iMac. The EFI doesn't choose which mode is used at startup, the kernel itself does that. If the kernel is only 64-bits, as it is with 10.9, it can only ever run as 64-bits.

Do you have a verifiable source that a stock Apple kernel can run in 64-bit mode on a 32-bit EFI?
You still have yet to produce a source for a statement that the EFI in a 2007 iMac is 32-bit.

Note: Failure to post a source when called for is against forum rules as outlined here: https://macrumors.zendesk.com/hc/en-us/articles/201327723-MacRumors-Rules-for-Appropriate-Debate

I quote from section 2 rule 1:

1. Sources. If you claim that something's a fact, back it up with a source. If you can't produce evidence when someone asks you to cite your sources, we may remove your posts. If you started the thread, then we may remove or close the thread.
 
I never claimed a fact only my research lead me to this site

http://www.ahatfullofsky.comuv.com/English/Programs/SMS/SMS.html

And why would apple give instructions on how to boot 64-bit if the system already boots that way.

Running the terminal command here has worked for me.

http://support.apple.com/kb/ht3773

Quoted from the link above.

"If your Mac uses the 32-bit kernel by default, but supports the 64-bit kernel, you can start up using the 64-bit kernel by holding the 6 and 4 keys during startup.
If your Mac uses the 64-bit kernel by default, you can start up with the 32-bit kernel by holding the 3 and 2 keys during startup."

Maybe putting those 10.6.2 kext in place on older machines that defaulted to 32-bit is the reason the 10.6.2 kext don't work for some users.

Is telling a EFI to boot 64-bit going to hurt? If what you say is true then, NO. What is it gonna hurt to tell something to do what it is already doing. Maybe it's already running 64 and your right. Either way this kernel flag in the boot plist is doing something else that work for me and maybe WILL WORK FOR OTHERS.

In the end isn't that what were all here for.

And I'm on my ipad right now and don't have access to my mac and even once a can run that script I'm not gonna run script given to me by someone I've been arguing with for 5 hours. And last time I checked:

http://www.everymac.com/systems/apple/imac/specs/imac-core-2-duo-2.0-20-inch-aluminum-specs.html

Is a third party site. If I think what is the root cause was fact you really think apple would support that fact. I'm pretty sure they might have a class action suit filed on them.
 
You posting your statements and defending them is enough to constitute them as fact. Apple created that knowledge base article because Snow Leopard wasn't fully stable in 64-bit mode on those machines and it's purpose was to allow developers to be able to update their programs and kexts for 64-bit mode. It wasn't until later with Lion that it became full stable on those models and defaulted to 10.7. Also, note that that article does not mention any version of Mac OS X other than 10.6. That means that it is outdated and irrelevant for 10.7 and newer.

Now you're reaching for straws. Everymac.com may be a third party site, but it is a highly respected and creditable site. Much more so than anything hosted on a comuv.com sub-domain. That site and its sub-domains borderline Wikipedia creditability.

Shall I break down the Terminal command so that you know exactly what every part in it does? Let's look at it now:
Code:
ioreg -l -p IODeviceTree | grep firmware-abi

ioreg: This is the command to list all information about your Mac in text tree format. You can view more information here: https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man8/ioreg.8.html

-l: This is the option that prompts it to show all data.

-p: This option tells it to traverse through the whole tree.

IODeviceTree: This tells it which tree to look through.

|: This is a standard UNIX pipe to pipe the output from one command to another.

grep: This program searches for matching strings within the inputted text. More information here: https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man1/grep.1.html

firmware-abi: Is the text that grep is to look for within the piped in data.


You see, nothing to worry about. Still don't believe me, read through the Apple man pages for those two commands, you'll see there's nothing malicious about that command.

I ask again, do you have a verifiable source that a stock Apple kernel can run in 64-bit mode on a 32-bit EFI? And what is your source that 2007 iMacs have a 32-bit EFI?
 
Okay so maybe I'm wrong in trying to describe the problem loading these 10.6.2 kext. And after a long heated debate I do concede that you were right and I am wrong. A 32-bit EFI cannot run a 64-bit kernel. But a 64-bit system can load the kernel in 32-bit mode. On older Macs running Snow Leopard the kernel booted the EFI in 32-bit by default. Other newer Macs booted in 64-bit mode by default. And maybe I'm wrong about that if so please correct me. I'm sure you will if I am. But maybe this is the reason these older Macs do not load the kexts properly. So when installing these kexts under Mavericks they do not load properly because Mavericks does not recognize a 32-bit kext. So maybe by telling the EFI to boot in 64-bit mode somehow fixes this error of the kext not loading properly.

And by the way I think EveryMac.com is a great site and I use it on regular basis.
 
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well that has been....interesting.

Certainly it makes sense as my Mac Pro 1,1 cannot run anything over 10.7.5 as it has the 32bit EFI, and my iMac 24 inch 2008 can run 10.10 so must have a 64bit efi from my crude understanding of it - that Apple removed the 32 bit part of the OS after 10.8.....

Anyhow - the issue seems to be this one of Kext Signing and its introduction with Yosemite. I do wonder if this is down to Apple realising that as OS X generates market share then with it will come more malicious attempts on the OS and therefore more risk....

I will try upgrading to 10.10 once more soon possibly next week and then will do the unsigned kext whotsit (technical term) and see what happens - hell theres always Time Machine again!!!
 
Frozen as well..

Dear all,

I have had this exact issue. Freeze from startup, from sleep, in the middle of apps. My screen has also freaked out at times and displayed very interesting and distorted pixels across the screen.

I have a iMac7,1 - Intel Core 2 Duo - ATI,RadeonHD2400.- OS X 10.10 (14A389)

Is there any fix or am I completely in the dust..
 
You can try the kext replacement method. That's the only real fix. Don't forget to nag Apple so that they look into this problem more and actually correct it.
 
You can try the kext replacement method. That's the only real fix. Don't forget to nag Apple so that they look into this problem more and actually correct it.

Is there a detailed pdf tutorial on how to do this, or instructions anywhere?

Thank you!
 
There are instructions earlier in this thread.

Intell, that is not the most helpful. Since you and the other have been arguing about which instructions are correct it would be great if you could quote/reference them. Thank you for your time!
 
After years of freezes, I am finally freeze free! Temp is stabilized too. Thanks Krystof and everyone here and in discussions.apple.com/thread/2384136 for this.
iMac 7,1
20-inch, Mid 2007
Graphics ATI Radeon HD 2400 XT 128 MB
Software OS X 10.9.5 (13F34)

  • Created folder on desktop called kext bu.
  • Copied System > Library > Extensions files AMD2400Controller.kext, AMDFramebuffer.kext, AMDSupport.kext and pasted them there.
  • Deleted originals.
  • Downloaded and opened the 10.6.2 kext files from http://blog.krzysztof-turek.com/apple-imac-8-1-freeze-problem-solution-en/
  • Downloaded and opened KextDrop.
  • Had to give permission in Security and Privacy since the program is from “unknown developer”
  • Dropped in ATI2400Controller.kext, ATIFramebuffer.kext, ATISupport.kext. Clicked Install. Closed KextDrop and restarted.

Checked to see if replaced kexts were in fact loaded:
$ kextstat | egrep 'ATI|AMD'
120 2 0xffffff7f82159000 0x45000 0x45000 com.apple.kext.ATISupport (6.0.6) <81 11 10 7 5 4 3 1>
121 0 0xffffff7f8219e000 0xca000 0xca000 com.apple.kext.ATI2400Controller (6.0.6) <120 81 11 10 5 4 3 1>
122 0 0xffffff7f81849000 0x22f000 0x22f000 com.apple.ATIRadeonX2000 (8.2.4) <81 11 7 6 5 4 3 1>
124 0 0xffffff7f82268000 0x12000 0x12000 com.apple.kext.ATIFramebuffer (6.0.6) <120 81 11 10 7 5 4 3 1>

Checked System information > Software > Extensions: shows all AMD kexts not loaded, new ATI extensions (version 1.6.6) are loaded.

Freeze-free!

freightrain12, when I eventually move to Yosemite I will have to run the Terminal command sudo nvram boot-args=“kext-dev-mode=1” to get the unsigned kexts to run.
 
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Hi, I've been having the frezze issue since upgrading to Snow Leopard on my 2007 imac. Ive tried a few fixes like clean install, tweaking fan speed ect. I also kept upgrading to the new OS each time hoping there would be a fix with no luck. I recently upgraded the RAM to 4GB and upgraded to Yosemite but the problem persist. I've been reading the thread and the last few suggestions seem to make sense. Can you all please chime in on where to start. Thanks!
 
Have you guys considered selling the iMac? It's like 7.5 years old by this time.

Just a thought. :eek:
 
Have you guys considered selling the iMac? It's like 7.5 years old by this time.

Just a thought. :eek:

What an apropos question given what I'm trying to do.

My mom's computer (mid-2007, 20", 2.0 Ghz C2D, 2 GB RAM) has had this issue since the beginning. I followed the threads back then to diagnose what was going on.

She dealt with the freezes during 10.6.8, and I hoped Lion would have resolved it (we know how that went). Given that she's not tech savvy, and lives 350 miles away, it was a challenge getting her computer back to a usable state. She no longer had the OEM install discs, so I had to walk her through the process of buying an external hard drive to back the computer up, torrenting OS X 10.6, saving that as a disc image since she didn't have any dual-layer DVDs, pressing the righ combo of buttons after the chime to boot from disc image, etc. About two years ago, she accidentally did the software update just before a critical art show at her house, and I told her that it was time for a new iMac - which she bought.

Fast-forward to Thanksgiving 2014, the 2007 iMac is still in the computer room, so I told her I would take it home to sell for her. I figured that after 3+ years, this issue would surely have been resolved by Apple.

I posted the Craigslist ad with it in a newly formatted 10.6 state saying I would upgrade if the potential buyer requested me to. Someone was interested, and asked if I could do the upgrade before they check it out. The computer faithfully began freezing as soon as it got to 10.6.8. It froze while downloading Yosemite from the App Store. After rebooting and attempting to install Yosemite, it froze while in the "Completing Installation" phase - although, this was not the usual kext related freeze, but a spinning beachball. That's where it is as I had to come to work. Hopefully it will get through that by the time I get home.

I'm pretty bummed out about this. How does one sell this machine in good faith knowing that it's not upgradeable? Who would buy it?
 
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Maybe at this point due to too many force shutdowns...But, it most definitely has the bad kext issue you've been discussing that Apple never addressed.

It's just frustrating that within a year or so of the computer being out of applecare, it was rendered non-upgradeable and has remained so ever since. Especially when it's clearly a software issue that Apple created.
 
So...I got home from work, and the installation completion screen was still beach balling. I force shutdown the machine and upon starting up, Yosemite was working. I didn't get to go through the registration splash pages, but that's cool because I am planning on selling this anyway.

About an hour of playing around so far, and I haven't had a freeze. I watched some trailers on Youtube, am browsing around here, and all is good.

Curiously, I went to watch a Daily Show clip and was greeted with an alert that I don't have Flash installed. I recall a few pages back it was recommended to always upgrade to the latest version of Flash...but what about zero Flash? Has this issue been encountered in the complete absence of Flash?
 

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Testing kext replacement with iMac 7,1 running Yosemite (OS X 10.10.1)

Thanks to @barryburek for spelling it out on this thread (and all those who have gone before him), I was able to install the 10.6.2 (ATI) kext files for my ATI Radeon HD 2400 XT 128 MB card on my mid-2007 20" iMac running Yosemite.

I have the same specs as @barryburek:
iMac 7,1
20-inch, Mid 2007
Graphics ATI Radeon HD 2400 XT 128 MB

Except that I am running OS X 10.10.1.

Here is what I did to update my kext files (following @barryburek):

1. Created folder on desktop called kext bu.
2. Copied System > Library > Extensions files AMD2400Controller.kext, AMDFramebuffer.kext, AMDSupport.kext and pasted them there.
3. Deleted originals.
4. Downloaded and opened the 10.6.2 kext files from http://blog.krzysztof-turek.com/apple-imac-freeze-solution-en/ (this takes a while to open in your browser - be patient!)
5. Downloaded and opened KextDrop.
6. Had to give permission in Security and Privacy since the program is from "unknown developer"
7. Dropped in ATI2400Controller.kext, ATIFramebuffer.kext, ATISupport.kext.
8. Clicked Install. Closed KextDrop and restarted.

At this point, after I rebooted my machine, I noticed that the graphics response was VERY slow. When I ran kextstat | egrep 'ATI|AMD' only the com.apple.ATIRadeonX2000 (10.0.0) came up. The other 10.6.2 ATI kexts I had previously installed were not loading.

So, after you reboot your iMac (if you are running Yosemite), this is what you need to do:

8. From Terminal, run: sudo nvram boot-args="kext-dev-mode=1" Enter your password when prompted.
9. Reboot your machine.

At this point, your 10.6.2 ATI drivers should load. Here is what I now show when I run the kextstat | egrep 'ATI|AMD' command in Terminal:

122 2 0xffffff7f8246c000 0x45000 0x45000 com.apple.kext.ATISupport (6.0.6) <81 12 11 7 5 4 3 1>
123 0 0xffffff7f824b1000 0xca000 0xca000 com.apple.kext.ATI2400Controller (6.0.6) <122 81 12 11 5 4 3 1>
124 0 0xffffff7f81a9f000 0x233000 0x233000 com.apple.ATIRadeonX2000 (10.0.0) <81 12 7 6 5 4 3 1>
126 0 0xffffff7f8257b000 0x12000 0x12000 com.apple.kext.ATIFramebuffer (6.0.6) <122 81 12 11 7 5 4 3 1>

Of course, since I just recently stumbled upon this thread tonight after living with iMac freeze issues for several months (if not the last year or two), I do not yet know if I am freeze free. But already I feel as though my system is both booting up and responding much more quickly than it did before.

Here's to hope!
G. Pasarescu
 
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