Dual boot on mac pro 4,1->5,1

[vworks]

Hi there!

I have 2 quick questions -
I have upgraded my mac pro from 4.1 to 5.1 via the firmware update thanx to Netkas!
(was B07, now it's B03)

I am currently on El capitan. I see I can directly go to High Sierra via the appstore.
Can I downgrade afterwards, and go back to El Capitan? I see that High Sierra upgardes also the SMC before upgrading the OS, so if I erase the disk and put El Capitan again, will the mac pro work, will it let me run it since it is not the same SMC as before?

And second question - can I install High Sierra on a second partition, keep El capitan for now and run Snow Leopard (which I have on a third partition) like I always did? Won't High Sierra mess up the partitions with APFS making me not able to boot on Snow Leopard for instance?

All partitions I am talking about are on SSD.

Thanx!!

 

[justinkr]

I don’t know what is your reason to keep all 3 version. If you wanted to use the older version you shouldn’t upgrade. You should stayed on the 4,1 and upgrade when ur committed to use latest os x. And I don’t think anyone has tired this complicated thread because it’s not worth it.

 

[vworks]

I have some software running on Snow Leopard. I will keep only High sierra and Snow Leo if High sierra is OK for me, but for now I want to test it.

 

[justinkr]

High Sierra will support most software because every software engineering upgrade their software to compact with newer version. For me I have 2 mac pro one is 07 and running 10.9.5 and one is 09 upgrade to 5,1 12 core. I use it separately. And I don’t regret my upgrade.

 

[Matty_TypeR]

the firmware upgrade does not include the SMC you are stuck with SMC version F5 even if upgraded to a 5.1. on 138 boot rom. what it will let you do is have 1333mhz ram speed and be able to run Mojave or HS also available are CPU upgrades.

as for your bootable OSX versions I see no point in keeping leopard as its security is very poor, El captain still gets security updates I believe. but of course what OSX versions you choose to run is your choice.

 

[vworks]

he firmware upgrade does not include the SMC you are stuck with SMC version F5 even if upgraded to a 5.1.

Sorry, I know that - I meant the ROM that High sierra upgardes, not the SMC. Will this new ROM be ok if I downgrade to El Capitan?

 

[justinkr]

I believe it will work like the other normal downgrade we have done in the pass. But I’ve never tried and promise u that.

 

[crjackson2134]

The firmware won’t OS-Block you. So it says in other threads where it was tested. I haven’t do that though, I have no use for it.

 

[orph]

yes you can have lots of copes of osx installed on different drives or partitions
when installing a new copy of osx i always keep a image/backup partition of my old install of osx encase any apps i need brake.

firmware ect have nothing to do with booting.

so if you want have windows,linux,mac osx10.9/10.10/10.11/10.12 ect all installed on different partitions

if you got your copy of osx from the apple shop check your past "purchased" items to see if you have the old versions of osx on the list, if it's not there it's less easy ^^

 

[vworks]

Thank you!
(I always keep copies of my os installers, have them all from panther to Mountain Lion)- + El Capitan if needed

 

[orph]

i keep the last version around for a while on a small partition just for safety, always keep my files off my os install so it's never that big (just apps and osx all work files on data drive).

it is true as mentioned that for security best not to take old copies of osx online but relay if your just using them for legacy software and doing daily tasks and online stuff on a newer version of osx it's fine.

wont be long till we will have to VM old copies of osx for legacy apps ^^