Snow Leopard on 2011/2012 MBP

Discussion in 'MacBook Pro' started by Guzaking, Mar 4, 2015.

  1. Guzaking macrumors member

    Mar 4, 2015
    The 2 different types of 17" MBP made in 2011/2012 the MC725LL/A and MD311LL/A are almost the same, the Late 2011 having a few minor upgrade tweaks, but it was shipped with Lion OSX and some people tell me that an MBP shipped with whatever OSX it has is the last OSX that you can downgrade too, back to its original OSX. I don't know how accurate this is?

    But the MC725LL/A was shipped with the Snow Leopard OSX. So I'm wondering since both these laptops are so close in compatibility, could you theoretically and successfully install Snow Leopard on the Late 2011/2012 MBP? Thank you in advance for your insight.
  2. redheeler macrumors 604


    Oct 17, 2014
    From what I hear it is in fact possible to downgrade a late 2011 MBP to Snow Leopard. This is the only exception to the shipping version minimum that I know of.
  3. matty1551 macrumors 6502

    Jul 7, 2009
    This does in fact work but you're gonna need the original install disc. Almost all SL dvd's or images are 10.6.3 which isn't supported. 10.6.6 or later will work.

    I had to pay apple $20 for a replacement install disc recently.
  4. maflynn Moderator


    Staff Member

    May 3, 2009
    As long as the components hadn't changed between those two models, it may be possible to downgrade. While technically true that you cannot downgrade below the version of OSX that was shipped with the computer there are some exceptions to that.
  5. cjmillsnun macrumors 68020

    Aug 28, 2009
    There is one way to find out. Using a machine you know works with Snow Leopard, install to a portable hard drive and run all software updates, to make sure it is as up to date as can be.

    Take this portable HD to the MD311LL/A and attempt to boot from it.
  6. Guzaking thread starter macrumors member

    Mar 4, 2015
    but if it is the original install discs, then those original discs will be the Lion OSX discs which originally comes with the M311LL/A so do you mean that i could use original install discs from another MC725LL/A for the later Late 2011 model?

    Also, I have purchased SL from the Mac Store and it is a 10.6.3 version as you described. So you are saying this isn't supported? I could not use this retail store bought SL 10.6.3 disc to do a fresh OSX install on the 311, or only on the 725 or both?
  7. Bomb Bloke macrumors regular

    Bomb Bloke

    Feb 12, 2015
    Tasmania (AU)
    It is very unlikely that you'll be able to install Snow Leopard directly onto a Late '11 MBP using any official installation disc. All releases of that model were running Lion out of the box, which means Apple probably never coded suitable Snow Leopard drivers, let alone had the inclination to put them onto Snow Leopard installation media. It's also the case that you generally cannot use a retail Snow Leopard installation disc on any system that shipped with a later version of OS X (including later versions of Snow Leopard itself).

    It may be possible to get Snow Leopard running with a bit of trickery, though. I'd use the older Macbook to set up 10.6 on an external USB drive, boot off that, and update it fully. You could then connect the drive to the later machine and boot off it.

    Even if it "works", you may find it doesn't work "properly". It's possible that with a bit of research, you might be able to locate and copy across any required-but-missing driver files and/or kexts from your Lion install into the Snow Leopard install.

    If you're able to get that going, then great! At that point you can go ahead and image the USB drive's contents directly onto the later MBP's internal drive, either setting up a dual-boot or replacing Lion completely.
  8. matty1551 macrumors 6502

    Jul 7, 2009
    Bomb Bloke is correct. This won't work with a late 2011 or later but it WILL work on an early 2011. Sorry for not clarifying.
  9. librarian macrumors regular

    Sep 24, 2011
    It does work but you need to find the proper disk from the early 2011 models.
    There are some glitches tho. Updating from 10.6.6 to 10.6.8 fixes them because of updated video drivers (apparently 6750m and 6770m have the same driver and kext).
  10. Guzaking thread starter macrumors member

    Mar 4, 2015
    alot of yes's and no's it seems, but there is only 1 way to find out as you say but with the discs...install it yourself with an Early 2011 disc which at that stage I'm told is a later version of SL starting with 10.6.6 or above and no other earlier version of SL will install from the disc.

    So if someone bought a 10.6.3 retail version from the Mac Store which is what they mostly sold, then it wouldn't work. Has anybody actually tried this from this forum?
  11. cjmillsnun macrumors 68020

    Aug 28, 2009
    You can install the retail on any Mac that can run the retail version. Then do a combo update to the latest version (10.6.8) It will then run on any Mac that is capable on running Snow Leopard.

    And yes I have done it, so know that works for a fact.

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