Downgrading OS from preinstalled version on MacPro

Discussion in 'Mac Pro' started by Spyharpy, Mar 23, 2011.

  1. Spyharpy macrumors member


    Apr 12, 2003
    Bay Area, CA
    I currently have a PowerMac G5 2.5 Quad and after six years of reliable service, looking to upgrade to a MacPro 3.33 6-core. My questions lies on whether it may be possible to downgrade a MacPro to a lesser OS. The reason being is that I have PowerPC software that I may want to run. I recall my G5 coming with a certain version of Tiger and I had a slightly older version installed on an external drive. Trying to boot from it gave me a message that I needed to run the version of Tiger that came with the installer disc/preinstalled on the G5. From this, I'm led to believe that I couldn't go back to anything older and that it was hardcoded to prevent from doing so.

    The next OS, Lion, will not support PPC nor Rosetta. Since the current MacPro is a Snow Leopard machine supporting PPC using Rosetta, would a MacPro after Lion was introduced and came preinstalled with it be able to be downgraded to Snow Leopard? I don't need a new MacPro this instant and could wait until the next update which may happen towards the end of this year. If the downgrade would not be possible, then I'd buy a MacPro before Lion was released.

    Reading the Apple support page (, it appears that it can be downgraaded but some problems may arise. Another possibility comes to mind also. If I had an installer disc from a current Snow Leopard MacPro, I would think I could install it unless the preinstalled Lion MacPro is hardcoded to not allow it.

    Any thoughts?
  2. mif, Mar 23, 2011
    Last edited: Mar 23, 2011

    mif macrumors regular

    Feb 16, 2010
    What i would do in situation like that? I'd buy an extra internal hard disk. for snowie. Or vice versa
  3. Cindori macrumors 68040


    Jan 17, 2008
    It will not be an issue with the current Mac Pro, but the next Mac Pro, launching end of 2011 / start of 2012, will probably not run Snow Leopard because it will contain hardware that requires drivers that will be built into Lion only.

    You don't have to downgrade to use another OS. You have 4 hard drive bays in the Mac Pro. You can install 1000's of different operative systems if you want to.
  4. Goldfinger macrumors 6502

    Jan 7, 2006
    You won't be able to downgrade the next generation Mac Pro to Snow Leopard, nor will you be able to boot from an external drive with Snow Leopard on it. SL won't have the necessary drivers.

    Solution: keep the G5 or upgrade the software. You'll have to upgrade your computer eventually...

    Yes, another solution is getting a current gen Mac Pro and dual boot but what about the next time you upgrade ?

    I'd just upgrade the software if possible.
  5. dime21 macrumors 6502

    Dec 9, 2010
    Downgrades generally don't work well. Partly because Apple releases a new OS update each time a new model comes out, specifically to include drivers and support for the new model.

    Your two best bets are either to upgrade your software, OR after you buy the new machine, keep a second older machine around specifically to run the old software.
  6. dyn macrumors 68030

    Aug 8, 2009
    Either stick to Snow Leopard (which means buying the Mac Pro before summer), or upgrade the Powermac plus (!) the software.
  7. mif, Mar 25, 2011
    Last edited: Mar 25, 2011

    mif macrumors regular

    Feb 16, 2010
    Sandy would be nice (AVX), but my Nehalem really bit my wallet. Something like €5K.
  8. Joshuarocks macrumors 6502


    Mar 12, 2011
    Somewhere in Cyberspace
    I don't really think Sandy Bridge i going to make a huge difference to a 2010 mac pro.. if anything, it will have thunderbolt and since someone told me already thunderbolt wouldn't help me with carbon copy cloner or time machine, its a waste..

    My 6-core 2010 will be my LAST Mac Pro.. I am sure it will run Lion and anything else after that.

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