Downgrading from 10.8.4 Mountain Lion to 10.6.3 or 10.6.8 MBP Late 2011

It isn't possible to revert on that Mac model.

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However, a Tier 1 Apple Tech Support guy just told me (on an official call) that if I

- Go into disc utility in ML

- Erase my main HDD

- Pop in my Snow Leopard Disc

- Boot

You use the DVD that originally came w/your computer, DVD#1. To reinstall the OS, you use DVD#2.

Clicky click--—> Erasing disks securely

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Start up from your install disc, go to Disk Utility and select the disk and click erase - to securely erase data click Security Options and Erase Free Space which will entirely wipe your disk, overwriting it with zeros so that no data is recoverable.

See KB Article: http://support.apple.com/kb/PH10727 OS X Mountain Lion: Restore your computer’s software

http://support.apple.com/kb/ph11273 OS X Mountain Lion: Erase and reinstall OS X

http://support.apple.com/kb/PH6817 Mac OS X 10.6: Restoring your computer’s software

Late 2011 MBPs came with Lion pre-installed. Basically, you cannot install Snow Leopard on that model. Furthermore, three beeps at startup means you have bad memory, not the wrong installer disc. Whoever advised you on the telephone gave you bogus information.

Even if you could boot the computer from a version of Snow Leopard, it would be foolish to erase the drive. It would make more sense to create a new partition on the hard drive on which to install Snow Leopard. In this way you have both operating systems running in a dual-boot arrangement.

I would leave well enough alone.

Three beeps at startup can mean that the disk is too old. If it was a RAM issue, it would happen every time the computer was started up, not only when an attempt is made to boot it into a specific OS version.

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Three beeps at startup can mean that the disk is too old.

Where did you read this, Niel? I don't recall having done so.

You don't have those discs because none came with that model. Baby Boomer is right about some earlier models, but not about yours.

rogueguineapig: If you can't find the gray disks, use an older Mac to install 10.6.3 onto an external drive and then run the 10.6.8 combo updater on that system. This will give a definitive answer on whether or not it's possible without them.

Kappy: Numerous threads on these boards have mentioned this.

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Regardless, you cannot boot your model from a retail Snow Leopard DVD. You did not get any gray labeled discs with your computer because it came with Lion pre-installed. You cannot install Snow Leopard on that model as much as you would like to (unless you have a different, earlier model that did come with Snow Leopard from the factory - Early 2011 or earlier.)

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Thanks, but I must confess not remembering seeing this in other threads. I was hoping perhaps you knew of an Apple article explaining it. Thanks, anyway.

1. No, the drive doesn't need to be blank.

2. It can be an USB or FireWire drive.

3. Plug the drive into that computer and start it up with the Option key held down.

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