EFI hack to make iMac recognize CPU properly?

Discussion in 'iMac' started by Anonymous Freak, Apr 22, 2013.

  1. Anonymous Freak macrumors 601

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #1
    I have an iMac 7,1 ("Mid 2007", the first Aluminum iMac.) It was originally a 2.0 GHz model with the "Merom" chip. I upgraded it with a 2.6 GHz "Penryn" CPU, and it works just fine. With one caveat...

    OS X doesn't recognize the CPU properly. In Windows via Boot Camp, it shows up just fine as a Core 2 Duo at 2.6 GHz. But in OS X, it shows up as "Core 2 Duo 700 MHz." Multiple rounds of benchmarking show it is definitely operating at 2.6 GHz speeds (more than 30% faster than the previous CPU, which, between the raw speed boost and the architectural improvements is about right.)

    The problem is iMovie apparently sees "700 MHz" and decides that's too slow to import AVCHD. Thus, even though it's faster than my other iMac (previous-gen white-plastic Core 2 Duo 2.0 GHz,) it won't import video where my older iMac will.

    My nasty workaround has been to import video on the white iMac (slow) then copy over WiFi to the Aluminum iMac (takes forever - they're at opposite ends of the house.) I know there are hacks from the Hackintosh community to make Hackintoshes fake certain CPU info, but since this iMac is fully supported in Mountain Lion, I'd rather avoid using boot loaders that are unecessary.

    Does anyone know of any way (EFI hack, boot-time kext change, etc,) to let OS X know the proper speed? (The way there was a CPU-speed-hack to convince OS X Leopard that you had a fast enough PowerPC system to install.)
     
  2. Intell macrumors P6

    Intell

    Joined:
    Jan 24, 2010
    Location:
    Inside
    #2
    You'll have to use a bootloader and a custom SMCbios.kext to get it to work. Or you could sell that CPU and get a supported one, up to 2.8Ghz.
     
  3. Anonymous Freak thread starter macrumors 601

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #3
    That's the problem, the CPU isn't supported on this model. This model has, as its fastest CPU, the power-hungry 2.8 GHz "Extreme" CPU - and then only on the larger 24" model. (Which has better cooling.) Benchmarks show my Penryn 2.6 GHz model is roughly equal to the 2.8 GHz Merom in speed, so I'd rather keep the cooler-running CPU.

    Yup, I was afraid of the custom bootloader/kext routine. If it comes down to it, I guess that's what I'll have to do.
     
  4. Intell macrumors P6

    Intell

    Joined:
    Jan 24, 2010
    Location:
    Inside
    #4
    The 20" is very capable when it comes to running the 2.8Ghz. It's power supply is able to handle it, as can it's very designed cooling.
     
  5. Anonymous Freak thread starter macrumors 601

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #5
    heh. But I already *HAVE* a 2.6... :p
     

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