Previous 1 2 Next 15 Replies Latest reply: Mar 29, 2014 1:54 PM by Grant Bennet-Alder
The Jimmonator Level 1 (0 points)

I recently have been trying to downgrade from OS X Lion to Snow Leopard. It's a pain in the ***.

My Mac Pro has 3 hard drives, the third one I don't use at all so I decided to restore the hard drive to the disk image of the Snow Leopard OS X install DVD. I read multiple articles saying this was one of the ways to do it.

I then chose to restart the Mac from the third hard drive (the one which was now a snow leopard os x install drive) and the mac pro simply will not boot now. Holding shift to go into safe mode, option to boot from a different hard drive or recovery doesn't work, all I have is a black screen. no signal to my monitor at all. I can hear the machine working fine.


It seems like I basiaclly need to force my Mac to boot from the first hard drive with lion again but right now I simply can't think of a way. if i could just reformat every hard drive in the mac i would!


Any help would be appreciated

  • Kappy Level 10 (265,914 points)

    Here's how you choose to boot from another drive:


    Boot Using OPTION key:


      1. Restart the computer.

      2. Immediately after the chime press and hold down the

          "OPTION" key.

      3. Release the key when the boot manager appears.

      4. Select the desired disk icon from which you want to boot.

      5. Click on the arrow button below the icon.


    Downgrade Lion/Mountain Lion to Snow Leopard


      1. Boot from your Snow Leopard Installer Disc. After the installer

          loads select your language and click on the Continue

          button. When the menu bar appears select Disk Utility from the

          Utilities menu.


    Booting From An OS X Installer Disc


    1. Insert OS X Installer Disc into the optical drive.

      2. Restart the computer.

      3. Immediately after the chime press and hold down the "C" key.

      4. Release the key when the spinning gear below the dark gray Apple

          logo appears.

      5. Wait for installer to finish loading.



      2. After DU loads select your hard drive (this is the entry with the

          mfgr.'s ID and size) from the left side list. Note the SMART status

          of the drive in DU's status area.  If it does not say "Verified" then

          the drive is failing or has failed and will need replacing.  SMART

          info will not be reported  on external drives. Otherwise, click on

          the Partition tab in the DU main window.


      3. Under the Volume Scheme heading set the number of partitions

          from the drop down menu to one. Set the format type to Mac OS

          Extended (Journaled.) Click on the Options button, set the

          partition scheme to GUID then click on the OK button. Click on

          the Partition button and wait until the process has completed.


      4. Quit DU and return to the installer. Install Snow Leopard.


    This will erase the whole drive so be sure to backup your files if you don't have a backup already. If you have performed a TM backup using Lion be aware that you cannot restore from that backup in Snow Leopard (see below.) I suggest you make a separate backup using Carbon Copy Cloner.


    If you have Snow Leopard Time Machine backups, do a full system restore per #14 in Time Machine - Frequently Asked Questions.  If you have subsequent backups from Lion, you can restore newer items selectively, via the "Star Wars" display, per #15 there, but be careful; some Snow Leopard apps may not work with the Lion files.

  • The Jimmonator Level 1 (0 points)

    this would have been very helpful, unfortunately...


    my mac simply will not boot into any mode at all, when I hold the option key, I still have a black screen, when i try to boot from the disc and hold C, still a black screen (i think the disc is spinning though? is this now a visual problem? this mac pro is from 2006 but has a HDMI slot? was it upgraded and might this be affecting the visual link in anyway? im just guessing here).


    Basiaclly.. black screen.

  • Kappy Level 10 (265,914 points)

    Do you hear a startup chime? You might try:


    Resetting your Mac's PRAM and NVRAM

    Intel-based Macs: Resetting the System Management Controller (SMC)


    to see if that fixes the black screen issue. When you cannot get even the gray startup screen when booting from an installer DVD that usually indicates some sort of hardware problem. If you have the original installer discs that came with the computer when it was new, then you can run the Apple Hardware Test. I'm afraid this about all I can suggest at this point.

  • The Jimmonator Level 1 (0 points)

    ****, thought you almost fixed my mac then. The chime was incredibly quiet beforehand, i mean incredibly quiet! After resetting the PRAM and NVRAM the machine restarted and the chime was louder. I thought i was about to get signal and it would begin to load but still no luck. tried the SMC too but still nothing. if this is a hardware problem why was this not happening before?

  • Kappy Level 10 (265,914 points)

    Well, the chime is good news. But too bad nothing else changed. I take it, then, that you are still unable to boot from your retail Snow Leopard DVD? You did not say if you had the original restore discs for the computer.

  • The Jimmonator Level 1 (0 points)

    Well here is where other problems come in, the disc tray in this mac pro is very fiddly, in fact im holding the eject key whilst the mac pro's power is on and it simply won't do anything. I tried to connect an external DVD drive and put in the snow lepoard discs and held C but still nothing. I don't have any of the original discs that it once came with.

  • Kappy Level 10 (265,914 points)

    Do you have another computer with a working optical drive and a Firewire cable you can use to connect the two?

  • The Jimmonator Level 1 (0 points)

    Yes, I have a Mac Mini with an optical drive, i do not however have a firewire cable. I can get one in the morning if that will be of help? Am I going to try booting with the Mac Pro as a target disc? I read about this and wondered if it would help.

    Would you guide me through it?

  • Kappy Level 10 (265,914 points)

    You would be using Target Disk Mode. You connect the Firewire cable between the two computers both of which, in your case, are FW800 ports. You boot the Mac Pro into Target Disk Mode by booting the computer and after the chime pressing and holding down the "T" key until the TDM screen appears.


    Then boot the Mini from your Snow Leopard DVD. Now for this to work your Mini must be able to boot from a retail Snow Leopard DVD. That means the Mini must be a Late 2009 or earlier to an Early 2006 model if it has a Core Duo CPU. After 2009 the Minis required a later version of Snow Leopard that was never released on a retail disc.


    If you can boot the Snow Leopard DVD, then you can open Disk Utility from the installer's Utilities menu in order to partition and format the third drive and then install Snow Leopard onto that drive.


    Now there is a caveat here. TDM will only work with the drive that is in Bay 1 of the MP. So you will need to swap positions and put the Bay 3 drive into Bay 1, and the Bay 1 drive into Bay 3.

  • The Jimmonator Level 1 (0 points)

    Hm, well my Mac Mini is a 2010 model and I don't believe booting the Mac Pro pressing any certain keys in particular does anything now. It seems like it just doesn't want to give me a video connection no matter what so there may be another problem in that area. I'm going to take it for repairs tomorrow, I want to get it up and running as soon as and I also have no experience changing swapping the location of hard drives but I appreciate all your help. I'll let you know how I get on

  • Kappy Level 10 (265,914 points)


  • The Jimmonator Level 1 (0 points)

    i'm just taking stabs in the dark here considering I don't know much about the insides of Mac Pro's, but the graphics card is an ATI HD5770 and so was upgraded (this mac pro is from 2006), is there anyway it suddenly just doesn't want to work with the mac anymore? it seems like the display just doesnt want to work

  • Kappy Level 10 (265,914 points)

    Yes, that's possible. I've used that card in mine for a couple of years now, but there's no rule that says it can't be defective. It's difficult, however, to work on hardware through these forums. You are wise to take it in for repair under the circumstances.

  • tinmar397 Level 1 (0 points)

    My macpro won't start (actually stops 1 second after pushing the power button) at home but works perfectly well at the repairer. Could someone help me with that problem please?

Previous 1 2 Next