Downgrading to Leopard on a new 27" iMac

Discussion in 'macOS' started by simonb1975, Jul 23, 2010.

  1. simonb1975 macrumors newbie

    Jul 23, 2010
    Hi, please help

    I have a new 27" 2.66Ghz Quad Core iMac which has got 10.6 installed. Does anyone know if I can go back and install 10.5?

    Reason being, we run a content management system using quark 7.5 and are unable to upgrade to v8. There are operating issues running quark 7.5 on 10.6 and if I can go back to 10.5 that would solve everything.:confused:
  2. eawmp1 macrumors 601


    Feb 19, 2008
    Macs can't run OS's that predate version they shipped with.
  3. slpdLoad macrumors 6502a


    Jun 10, 2009
    In general, you should not install an operating system older than what the Mac originally shipped with, mostly due to drivers that are specific to your system and may not be present on the older OS.

    For critical systems, you should have both hardware and software backups and test new upgrades before committing to them.

    It may be possible to run 10.5, but you'll need to have an updated version (newer than 10.5.7 I believe). I would not recommend attempting to install directly from a Leopard retail disk on the new iMac.

    Instead, you'll need a secondary temporary Mac that is capable of running Leopard. Boot the new iMac in Target Disk Mode, and boot the older Mac from the Leopard install disk. Connect the two computers with a FireWire cable, and install Leopard onto the new iMac's hard drive using the old Mac. After this completes, run a few rounds of Software Update to ensure that you are running a fully up-to-date 10.5.8. After this is complete, shut down the old both Macs, disconnect the cable, and start up the new iMac normally with its now-10.5.8 drive. If you're lucky, everything will work properly. But it may not even boot, and you will need to reinstall with the 10.6 restore media that shipped with it.
  4. larkost macrumors 6502a

    Oct 13, 2007
    There is absolutely no chance that 10.5 will be able to support the i5 or i7 iMacs (quad cores). It does not have the video card drivers nor the chipset drivers for lots of things on the motherboard (including the processor).

    The bigger question is why you think you need to or should be doing this. That is probably the question that can be solved.
  5. mac2x macrumors 65816

    Sep 19, 2009
    You mean older that what the machine shipped with, right?
  6. slpdLoad macrumors 6502a


    Jun 10, 2009
    Doh. Thanks, edited.
  7. wilsonlaidlaw macrumors 6502


    Oct 29, 2008
    We have 4 machines running Slow Leopard and 2 still running Leopard. No doubt at all in my mind, that Leopard is more stable, gets few SBOD's (Spinning Beachballs of Death), Airport issues, program freezes etc. I just hope that 10.7 (Faster Cat?) is better.

  8. simonb1975 thread starter macrumors newbie

    Jul 23, 2010
    thanks for your comments, its a shame you can't revert to 10.5 but I can understand why. I can get around this by installing a previous version of Java (1.5) on 10.6 then our content management system is good to use...;)
  9. peregrina macrumors newbie

    Nov 3, 2010

    I have a similar situation... DVDSP 4.1.2 is not stable in SL; but it works fine under 10.5.8
    I don't edit video, so I only use DVDSP; and the upgrade is pricey
    This is bad news from me :confused:

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