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Acidanthera proposed modified installers from 10.6.7 Images for MacBookPro8x and iMAc12x here, but they hang on ethernet (most probably driver) on the cMP5,1.

I have modified this script (originally created for a DVD installer creation) for a SL USB universal installer creation. The created installer from the link in the first post (please convert .toast to DMG as described here) works fine in cMP5,1 , but I have no way of testing it on other machines.
All the script does is changing:
Code:
for ( var i = 0; i < machineCount; i++ ) {
    if ( modelProp == hwbeSupportedMachines[i] ) {
        return true;
    }
}

With this:
Code:
for ( var i = 0; i < machineCount; i++ ) {
    if ( 1 ) {
        return true;
    }
}

Code:
#!/bin/bash
clear

destination=~/Desktop/Mac\ OS\ X\ Install\ DVD

#make destination folder
[ ! -d "$destination" ] && mkdir "$destination"

#make sure disc is in drive
while [ ! -d /Volumes/Mac\ OS\ X\ Install\ DVD ] ; do
echo Please mount Mac OS X Install DVD image and press Enter
read
done

#get device node for block copy
device=$(diskutil info /Volumes/Mac\ OS\ X\ Install\ DVD/ | grep Node | cut -f2 -d:)

#create disk image from device (retains Finder window custom background)
echo "Creating Disc image at $destination, please wait..."
/usr/bin/hdiutil create -srcdevice $device -format UDRW "$destination"/Mac\ OS\ X\ Install\ DVD.dmg

#disk image using source folder (loses custom Finder background)
#/usr/bin/hdiutil create -srcfolder /Volumes/Mac\ OS\ X\ Install\ DVD/ -format UDRW "$destination"/Mac\ OS\ X\ Install\ DVD.dmg

#eject media
hdiutil eject /Volumes/Mac\ OS\ X\ Install\ DVD/

echo "Modifying Image"

#mount r/w image
hdiutil attach "$destination"/Mac\ OS\ X\ Install\ DVD.dmg

#expand OSINstall.mpkg
/usr/sbin/pkgutil --expand /Volumes/Mac\ OS\ X\ Install\ DVD/System/Installation/Packages/OSInstall.mpkg /Volumes/Mac\ OS\ X\ Install\ DVD/System/Installation/Packages/OSInstall.expanded

#modify Distribution script in place with no backup
/usr/bin/sed -i '' "s/modelProp\ \=\=\ hwbeSupportedMachines\[i\]/1/g" /Volumes/Mac\ OS\ X\ Install\ DVD/System/Installation/Packages/OSInstall.expanded/Distribution

#modify Distribution script in place with backup (for sissies)
#/usr/bin/sed -i '.original' "s/modelProp\ \=\=\ hwbeSupportedMachines\[i\]/1/g" /Volumes/Mac\ OS\ X\ Install\ DVD/System/Installation/Packages/OSInstall.expanded/Distribution

#remove original OSInstall.mpkg package
/bin/rm -rf /Volumes/Mac\ OS\ X\ Install\ DVD/System/Installation/Packages/OSInstall.mpkg

#flatten new package
/usr/sbin/pkgutil --flatten /Volumes/Mac\ OS\ X\ Install\ DVD/System/Installation/Packages/OSInstall.expanded /Volumes/Mac\ OS\ X\ Install\ DVD/System/Installation/Packages/OSInstall.mpkg

#remove expanded folder
/bin/rm -rf /Volumes/Mac\ OS\ X\ Install\ DVD/System/Installation/Packages/OSInstall.expanded

### image is now ready to be burned ###

echo "Ejecting the original Image"

#eject disk image
hdiutil eject /Volumes/Mac\ OS\ X\ Install\ DVD/

#convert the RW image to Read Only for restore

echo "Convering RW to RO image"

/usr/bin/hdiutil create  "$destination"/Mac\ OS\ X\ Install\ DVD\ Converted.dmg -format UDZO  -srcdevice "$destination"/Mac\ OS\ X\ Install\ DVD.dmg

echo "Deleting RW image"

#delte the RW image
/bin/rm -rf "$destination"/Mac\ OS\ X\ Install\ DVD.dmg


echo 'Please type in separate terminal window "diskutil list" and make sure that there is only one "external" device and it is the USB you intend to reformat. Press Enter'
read

#get external usb device

usb=$(diskutil list | grep external | cut -c 1-10)

echo "erasing USB"

#Erase the USB
diskutil eraseDisk JHFS+ Untitled $usb

echo Restoring to usb
sudo asr restore --source "$destination"/Mac\ OS\ X\ Install\ DVD\ Converted.dmg  --target /Volumes/Untitled  --erase -noverify
 
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I'd like to downgrade my Mac Pro 5,1 from Lion to snow leopard. No matter what I've tried, it simply won't work.

I tried flashing a retail disc to a USB, and then booting from that, but it gets stuck on an apple logo.
I also flashed the disc that (supposedly) came with the computer, but it spins on the apple logo for a bit, and then shows a "no entry" sign in place of the apple logo after about a minute or so.
(Image of the mac pro snow leopard disc: https://archive.org/details/691-674...nstall._Mac_OS_v10.6.4._Disc_v2.0_2010_DVD_DL)

Is there any way to install snow leopard on this computer? Or is there some sort of firmware lock that prevents snow leopard from being installed after a newer OS is installed?
have 2008 MP w/ snowleopard installed from apple retail DVD on PCIe/SATA RAID0. transplanted PCIe/SATA drive into my mid 2012 MP5,1 and it boots and runs just fine. i even updated the BootROM in the 5,1 to v. 144.0.0.0.0 to get max speed from PCIe/NVMe, and still no problemo. not sure what's causing your issue. could be vid card? see: http://blog.greggant.com/posts/2018/05/07/definitive-mac-pro-upgrade-guide.html#aftermarket-gpus
 
have 2008 MP w/ snowleopard installed from apple retail DVD on PCIe/SATA RAID0.
Sure, there is no problem if you install the SL on another machine, update it and drop it in the cMP5,1. Not everybody though has another machine that supports retail SL DVD. If the machine came with restore SL DVDs non of the previous retail DVDs not even restore DVDs will work on it. From my testing even later restore DVD versions modified to allow booting on cMP5,1 hang on boot due to the lack of specific to cMP5,1 drivers. The latest retail SL DVD version is 10.6.3 and the cMP5,1 restore DVD is 10.6.4. Clearly the drivers are not there yet.
As far as the specific image in the first post I also had issues creating a bootable DVD/USB from it.
It is important to know that if you mount the .toast file directly it will populate multiple partitions. So if you restore the mounted image it will never boot. You need to restore it to a single HFS+ partition and only then it will work. Hence the conversion to a DMG.
 
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Sure, there is no problem if you install the SL on another machine, update it and drop it in the cMP5,1. Not everybody though has another machine that supports retail SL DVD.

What i have found most useful is using the firewire target
mode, putting the Target Mac (eg. MP5,1) into it, and then use the supported SnowLeopard Mac to install SL from DVD or USB onto the target mac / and update it fully, before shutting it down.
sometimes, a fw400 to fw800 cable or adapter is needed to achieve this.
 
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Also you can attach a ssd to an usb-sata adapter cable or enclosure and just install it on the supported Mac.

Eventually edit/add the board-id, but most of the time the installed system just runs.
 
Hi, you can get the ISO DVD here:


Download it and burn a disc... that should do the trick...
I seem to remember the DVD from when I got my 2010-MP. The archive.org version is a .toast file. How do you get it onto usb / convert it to iso/dmg, then restore?
 
Quick couple of questions while I wait for the torrents to finish downloading...

1. Which one is better the v1.0 or v2.0 restore dvd, it looks like they both install the same version of Snow Leopard?
2. There is some mention of opencore above, is that required? My MP used to run Snow Leopard, if I recall correctly.
 
Quick couple of questions while I wait for the torrents to finish downloading...

1. Which one is better the v1.0 or v2.0 restore dvd, it looks like they both install the same version of Snow Leopard?
2. There is some mention of opencore above, is that required? My MP used to run Snow Leopard, if I recall correctly.
I did not compare. It would be nice to know. One of them might have more drivers.
 
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