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  • SwampFoetus Level 1 Level 1

    32bit only allows you access upto 4Gb of memory and usually means that the video memory has to be mapped/overlapped with the system memory.  e.g. if you have 4Gb of system memory and your graphics card has 512mb, then you'll only be able to use 3.5Gb of your system memory.  I'm not sure if this is correct for OS X, but it certainly is for Windows.


    64bit allows you to address memory greater that 4Gb and means that your video card memory doesn't have to overlap your system (as above, I'm not sure if that's just a Windows problem).  You also get a performance increase with 64bit apps, which was demonstrated at the WWDC a year or two back, but can't remember the reason for it.


    I'm not sure what the issues are around here with 32/64 bit and 7,1 models, as that model is fully 64bit (both EFI and processor), which is why it can run Mountain Lion and Mavericks (and theoretically any future 64bit OS X).  See here.


    6,1 models, however, are only half 64bit; 32bit EFI and 64 bit processor, which is why you can't get above OS X Lion (although you can do it with a hack).

  • LightningMike Level 1 Level 1



    Thanks for th explanation LOL.  I was worried that if I ran in 64-Bit mode 24/7 then I might actually slow down my mac rather than make it more efficient.  So even though Apple says 4 Gigs is max maemory for my machine, I am running 6 Gigs and its recognized.  My primary "application" is Adobe CS4 and mainly Photoshop CS4.  I don't do much of anything else in the way of extra programs.  I think CS4 will run under 64-Bit OK... but I will have to check.  I know it works, but whether its working well is unknown.


    Its been 3 days since the fix and no more freeze-ups I'm happy to report.



  • TK111 Level 1 Level 1

    Now there seems to be a similar problem with AMD GPUs in Macbook Pros.



    Personally, I'm going to be very wary of buying any more Apple products with AMD/ATI graphics in them, which is to say na gon do it.

  • Duster19 Level 1 Level 1




    I looked into my issue more and found that I wasn't actually deleting the AMD files when I dragged them out of the system folder. 



    * you must right click and choose delete.  This will prompt you for admin. approval and password.


    My ATI files are now showing enabled and I haven't had a freeze in 48 hours. 




  • LightningMike Level 1 Level 1

    Yeah... Well, unfortunately, I had a freeze-up yesterday which was 8 days.  Better than every 2-3 days but still a PITA.  I don't remember if I truly deleted any files or what.  I may have to repeat the process just to be safe if there's something creeping back in.


    Its my understanding that Mavericks boots in 64-Bit mode automatically right?  Or do I have to set some parameters to make sure it does.  I was only worried about about my Adobe CS4 suite, but so far Photoshop hasn't burped.

  • aieronimo Level 1 Level 1

    Mike, this might help you see if your iMac can be made to boot automatically into 64-bit mode.  I have no idea if Mavericks automatically boots that way, or if it is machine-dependent.


  • Duster19 Level 1 Level 1

    Another Update:  going on my 4th day without one Freeze.


    Seems that the Kext fix works with 7,1 iMac running 10.9.1 

  • Duster19 Level 1 Level 1

    Well, still no freezes since Feb. 22nd.


    I'm thinking the kext has stopped my random freeze problem again. 




  • aieronimo Level 1 Level 1

    Jan. 22nd - right, Duster19?

  • Duster19 Level 1 Level 1

    Opps...  Yeah Jan. 22nd.




  • Semih_TX Level 1 Level 1



    I have an early iMac 24 with ATI Radeon pro 2600. I have been running 10.9.1 with no problems since Maverick OS came out.  The screen freeze problem during Netflix happened 2 weeks ago, then again 2 days later. Finally, I got the "white screen of death".  Booted into safe mode and applied the "kext" fix mentioned on this post (moved/replacedcurrent AMD, ATI kext files with the older versions as suggested). Now, I am back to a functioning computer (still running 10.9.1). However, performance did slow down quite a bit, everything is slow to load; faint, vertical, red lines are visible in front of gray background (iTunes, outlook, etc).


    What does this "kext" fix do? Am I not using my ATI Radeon graphics card anymore? Do I need to replace the graphiscs card or is this a software problem?

  • aieronimo Level 1 Level 1

    Semih_TX - I did not experience your issues with the slow loading and faint lines.  The kext fixes install old software drivers for your graphics card.  You are using your ATI card, just with drivers from a few years ago -- before Apple upgraded them in a way that causes the graphics card to crash the system.  You don't need to replace the graphics card, so long as you use the old drivers with it.

  • aieronimo Level 1 Level 1

    Anyone install 10.9.2 yet?  Does it require a reloading of the old kext files, or does it leave those files alone?  Thanks.

  • JudgeE Level 1 Level 1

    Hi, I'm a long time follower of this thread, and user of the KrzysiuTurek kext fix on page 21 and instructions by CWGuide on page 28.  Then upgraded to Mavericks and used the awesome instructions by freandc on page 102.


    I installed 10.9.2 yesterday and had freezes right away. So I did the normal kext fix using kext helper, WITHOUT replacing the AMD files again as described on page 102 and things have been smooth sailing for the two days now.


    My 2007 iMac with AMD 2400 card works as good as the day I bought it.


    If any of you are debating trying the kext fix, DO IT. My iMac used to freeze 10-15 times a day with all the other symptoms, i.e. (grey screen, stripes on screen, beach ball). I went to the Genius Bar mulitple times without resolution and was told to replace my graphics card, hard drive or motherboard. THEN I found this thread and solved all my problems. Thank you to all who have contributed to this solution for this unfortunate problem to a issue long forgotten and overlooked by Apple.


    I am current on 10.9.2 running like a champ. We will see how long this fix will take us...

  • bobtibb Level 1 Level 1


    I have just installed the 10.9.2 update from Software Update. I allowed the system to go through it's motions and it re-booted fine. So, I checked in About this Mac to see what drivers had been loaded for my video card and it appears to have replaced my ATI kexts with AMD kexts for the 2600 Pro. Rather than wait for any problems to occur, I went through the kext fix again and installed the ATI versions and before rebooting, killed off the AMD versions (keeping them safe in a folder, first). Rebooted and checked About This Mac again. Sure, enough . . . the ATI kexts were accepted and loaded. You will need to ditch the AMD versions, otherwise the system will 'see' the AMD kexts first (alphabetical) and load them instead of your ATI versions. All seems to be ok.