Swap Boot drives? MacPro4,1 and MacPro5,1?

[James Steele]

So I got the Mac Studio to replace my MacPro5,1 12-core. So now I want to perhaps retire my MacPro4,1 6-core which has been my office machine and to this point, and move the MacPro5,1 12-core to the office.

My office MacPro4,1 is running High Sierra. My MacPro5,1 is currently running Mojave, but for office duty I want to downgrade to High Sierra as I'm for now very reliant on Bento for a database which won't work on Mojave or later. Not only that, I can go back to my non-metal Graphics card. The one I bought on Craigslist turned into a major bust. It runs so hot (I suspect the fans attached to the card are intermittent) that without all sorts of gymnastics with Fan Control, my Mac would freeze up due to heat on the Northridge Diode.

Since my MacPro5,1 12-core actually began its life as MacPro4,1 8-core until I did the firmware hack and installed new CPUs, I'm wondering if I might possibly get away with simply taking the High Sierra boot drive out of the MacPro4,1 and putting it into the MacPro5,1 and seeing if I can boot from it? I'm even using the same USB dongle modem in both computers.

I guess I'm going to try it. It would make life a lot less complicated. If it works... I'll clone the boot drive to a newer SSD and see if it works. Actually I may take one of my SSD's out of the 5,1, hook my raw drive dock up to the 4,1 and clone the boot drive, then take that SSD and put it in the 5,1 and see if I can instantly turn it into my office computer. Would be nice if that worked. If not, I could always do fresh install of High Sierra in the 5,1, then put the clone drive in one of the bays and use Migration Assistant. That's probably the safer way.

[mikehalloran]

I'm wondering if I might possibly get away with simply taking the High Sierra boot drive out of the MacPro4,1 and putting it into the MacPro5,1 and seeing if I can boot from it? I'm even using the same USB dongle modem in both computers.

Should work. I used to swap boot drives all the time when maintaining school networks and everything was on HDDs. Often, I was testing different OS on older hardware.

[James Steele]

I'm wondering if I might possibly get away with simply taking the High Sierra boot drive out of the MacPro4,1 and putting it into the MacPro5,1 and seeing if I can boot from it? I'm even using the same USB dongle modem in both computers.

Should work. I used to swap boot drives all the time when maintaining school networks and everything was on HDDs. Often, I was testing different OS on older hardware.

Nice. Well my clone is about done so I'll pop it in the MacPro5,1 and see if she boots up. If so, that will save me a TON of time!!

[HCMarkus]

I'm betting it worked.

[James Steele]

I'm betting it worked.

It did... but this is embarrassing... I launched Mail and tried to check my mail and it asked me for all the passwords to my many email accounts! I couldn't remember. I think I have them all written down somewhere. I really wish Apple's mail app let you SEE your email passwords by clicking a little "eye" icon and typing your admin password.

Anyway... I'm wondering if doing a fresh install of High Sierra and using Migration Assistant to move all that stuff over might be better and preserve email passwords in the meantime. Also, I mentioned elsewhere I''m thinking of getting an PCI card adapter and using the WD Black NVMe drive in the MacPro5,1. I imagine connected via PCI instead of SATA it would be much faster and 2TB would be luxury for my office machine.

[James Steele]

I'm betting it worked.

Oh yeah... and the other good thing about going down to High Sierra is:

1) APFS still works
2) I can put in my older, non-Metal GPU and ditch the messed up toaster oven GPU I got on Craigslist. Still frosts me that those people wouldn't take it back. I think one of the fans on it is intermittent and I don't have the patience, nor can I see the value in spending money to have someone look at that and fix it. Ugh... that was a complete waste of money.