Why won't my Mac Pro 5,1 boot Snow Leopard?

It should

by default it uses 64 bit kernel

OEM DVD was 10.6.4 but 10.6.3 may work

yoy may have software drivers that aren't

If it did not come with ANY DVD then will it boot into recovery mode?

It is possible it has Lion firmware, net install, network based Apple Hardware Test.

Hard to tell, but are you trying to boot off of one of your old Mac Pro 1,1 hard disks installed in the new Pro? Do you have any DVD's you can boot from instead?

When I migrated from a G5 to my Pro, I booted right off the old G5 hard disk, and the system had to install a couple of files, but it did work. Not saying I recommend it however.

10.6.3 is the retail version of 10.6 that was last released. If your Mac is newer than it, you will need to get the 10.6 installer disc that came with it for a nominal charge from AppleCare if it was lost.

You can't use another Mac's installer discs.

only 10..6.3+

Actually none of those will work. The Mac Pro 5,1 was released after March 15, 2010. As such only the discs labelled Mac Pro will work. If you lost them or they are damaged, call AppleCare for replacements. They will charge a nominal fee.

http://www.everymac.com/ultimate-mac-lookup/?search_keywords=MacPro5,1

Technically... but in real world 10.6.3 does have minimal basic support so you can run Software Update. It will boot.

It was one of those interim builds of OS X too, 10.6.4 which itself was a new build every week or two for first month's time.

That is different than past post retail releases. I didn't know that. Thanks.

Michael Sciascia wrote:

My old Mac Pro 1,1 died. I replaced it with a new Mac Pro 5,1. (dual Westmere quad core) Apple told me it would run Snow Leopard. The new machine recognizes my old Snow Leopard hard drives as start-up disks but does not boot past the gray screen apple logo....

...I need Rosetta back!

I took almost exactly the same route you have: 1,1 to 5,1 six core. And I booted off a clone of my 1,1 OS 10.6.8 boot disk which worked. However, before the purchase, I asked Apple Tech Support a number of times if a Mac Pro that came with Lion installed (i.e., after Lion's release date) would accept a Snow Leopard install and was told uniformly no, that it would have something built in (firmware?) to prevent it, so I ordered mine just before Lion was released. As The hatter says, it might have Lion firmware.

Just for kicks, have you tried booting from the 1,1 disk in Safe Mode?

The refurbished store is always a good place to buy tested and reliable, and of course just post the firmware version of both yours and some others. We have seen 'downgrades' go just fine.

Or, if you new Mac has Lion firmware then it has net-install and a mini-AHT ability in firmware and connected to Apple servers.

I don't see why they crippled and took UEFI and turned it into a means to push and force upgrades. Not every Pro Suite and user is ready for Lion yet. Software upgrade costs, and some needs at minimum more than a little tweak and push. Buying the 2010 I guess just got harder unless Specials (they still sell those 2009s too)

the only way to know and test is the EFI/SMC firmware version (system profile)

I don't trust what anyone elsse says, marketing clueless, other than try it yourself hands on experience.

So it sounds like they recently updated, and closed the avenue to pre-Lion OS forcing customers.

This is a very old post, but I found it when I tried and failed to boot my 2010 model 5,1 westmere 12 core from a Snow Leopard family pack install disk, in order to install the OS on a firewire attached hard drive. I then tried to boot from my original install disks that came with the Mac Pro, and it booted just fine from that one. My mac pro has never gone beyond Snow Leopard 10.6.8....

from:

MacOSX: versions (builds) for computers

What this shows is that if you can build a verion of 10.6.8 using another Mac, starting from a "Full Retail" DVD (so that "drivers for every appropriate Mac" are included) it will boot the Mac Pro 5,1 from 2010. Users here have determined that, since the 2012 model uses the same firmware with no significant new hardware changes, it will actually boot that one as well.

Starting with a DVD that "shipped in the box" with a different model Mac will not include the right drivers, even after update.

Grant,

I didn't try to boot a my 12 core Mac Pro with a gray "shipped in the box" disk from a different mac. The one that failed to boot my Mac Pro was a full retail family pac Snow Leopard disk... The one that did boot my Mac Pro was the gray disk that shipped with it. Still, I think your chart explains why my retail disk didn't boot it. It was 10.6.3, and my Mac was 10.6.4.