How to transition Windows from Mac Pro 2,1 to 5,1?

[hwojtek]

On my Mac Pro 2,1 I had a perfectly running Windows 10 installation. It was installed in legacy (MBR) mode a couple of years ago, with a set of drivers extracted from Bootcamp and from the manufacturers it worked like a champ. I have not used Bootcamp for installation, though, it was installed on a separate hard disk without using Bootcamp as an installation tool.
I just moved to a Mac Pro 5,1 and, quite obviously, I moved the Windows hard disk with me. Also, quite obviously, it doesn't start, giving a "DISK READ ERROR, press ctrl+alt+del to restart" error.

What I want to achieve: I want to run this particular Windows installation from this very disk in the 'new' computer.

The limitations:
- I DO NOT have any optical drive and will not have one until the epidemic goes away, so reinstalling from DVD is not an option
- I DO NOT have any other Windows computer
- I DO WANT to run Windows in legacy mode, as I am too worried about Windows in UEFI mode to mess up the NVRAM*
- I WILL NOT reinstall Windows from USB unless there is a way to force legacy install (see below)

The toolbox:
- I do have a number of actual Macs and a polished Ubuntu installation in VMWare.

What have I already tried:
- reinstalling: Windows boots from USB, however refuses to reinstall on the disk, as "on UEFI systems the disk must be GPT". I would have to reformat the disk, which is something I don't want to do
- bootloaders: I think this might be the right way, but I have zero experience with bootloaders. I installed rEFInd on an USB and booted from it. It shows me a "Windows legacy" option to boot, but ten minutes later it still does not boot, blinking a cursor instead.

While AFAIK bootloaders were intended for our Hackintosh friends to fool MacOS it's running on genuine Apple hardware, I believe there is a way to apply them in an inverse way: to fool Windows into thinking they are still running on a BIOS (legacy) machine. I do not have any knowledge of bootloaders though, so I have no idea on how to set them up.

* perhaps it's a superstition and there is nothing to worry about, perhaps there are tools to make sure the NVRAM is intact (are there any?) after Windows updates.
If it is safe to run UEFI (most voices are it's not, at least on a Mac Pro 5,1) would mean that theoretically a simple non-destructive MBR to GPT conversion should do. Is it possible from outside Windows?

In advance, thank you for your insights.

 

[StuAff]

Hmmm.....AFAIK, USB install will not allow CSM install, in any way shape or form. Having found this thread, which you might have seen yourself, I'd suggest the 32-bit EFI on the 2,1 might be an issue. Disk format should be the same, but the 5,1 definitely expects a 64-bit system. Is the install you're trying to move 64-bit? If not, that could be the problem. If it is 64-bit, it might be the mods required to get it working on the older Pro prevent it booting the newer one. There's also a thread here which might help (1,1s but 32-bit EFI again). If you haven't already, I'd recommend buying a copy of Winclone from twocanoes.com- both to backup the Windows drive, and because it may well help getting the problem sorted- even if it's a case of doing a clean Windows install then transferring everything. Winclone does support migrating Windows installs from one Mac to another- whether it'll work in this case, I have no idea, but it'd be worth a try. Should you need to do a reinstall, you'd want a DVD drive in or attached to the 5,1, as Remote Disc won't work with Windows install discs.

 

[hwojtek]

Yes, Windows is 64-bit.
Thanks for these threads, I did my research, but quite frankly I see I didn't read everything (yet).
There were absolutely no mods into this installation when done on 2,1 - it just went straight from the DVD as it was a regular PC, it was perfectly 32/64-bit agnostic.
I will have a look into Winclone (I have seen it has a simple GPT/MBR boot switching option), however I would prefer this installation to work as a legacy (MBR) boot, so Winclone would be one of my more desperate options

 

[Mikael H]

Windows isn’t Unix.
Expect a whole lot of problems if you change the chipset from under an existing Windows installation. If you still have the 2.1 and an extra disk to which you could make an additional clone, you could see if Acronis TrueImage might help in stripping out existing drivers and providing the ones you need for the 5.1.
Another option - which still requires an additional disk to not risk your existing data - might be to attempt to generalize your installation using `sysprep`.
In total, though, you’re most likely out of luck if reinstalling from scratch isn’t an option, given the differences between the machines.

 

[hwojtek]

Well, it took a while, but eventually I sorted it out.

TL;DR: the actual culprit here was a genuine Apple AHCI SSD pulled out of a 2014 Macbook Air, sitting in an el-cheapo Chinese PCIe adapter, causing the error.

Longer version: a couple of months ago I upgraded my Air and used its SSD as a scratch/project drive in the 1,1. The 2,1 running El Capitan and Windows10 (legacy mode) was happy with it.
Now I moved this adapter into the 5,1 and while Mojave used this disk just as happily as before, Windows was a non-booter due to "DISK READ ERROR, press ctrl+alt+del to restart".
Some 5 installs later I've found out that the only way to install Windows in this particular hardware scenario is to have them run in UEFI mode - as long as I had the Apple SSD on the PCIe card in the computer. If I tried legacy, Windows was throwing the disk error after first restart.
I converted one of the clones to UEFI, recreating the EFI disk structure of a genuine Windows installation (thank God for VirtualBox, as it allowed me to run yet another installation of Windows just to clone my original Windows 10 disk and tinker with a copy) and... lo and behold, it fired right up.
Straight swap. It took Windows some 20 minutes to sort out the basic drivers, the rest was taken care of by Bootcamp drivers using Brigadier.

So it is definitely possible to just move a Windows disk from one Mac to another and have it booting, provided the computer has the ability of booting this particular disk scheme (either MBT or UEFI). Most Macs do - and provided you don't have an "exotic" storage card.

This wasn't what I wanted, though, I wanted Windows 10 in legacy mode. And that was not the end of the issues.
As it turned out, if I was in W10 UEFI with the Apple disk in the PCIe adapter, installing any AMD GPU driver (both genuine Windows update or Catalyst drivers) resulted in the infamous TDR crash, rendering the computer unusable. Once I removed the Apple SSD and it's PCIe adapter, my R9 280x was finally updated with the proper drivers.

It was then now only a matter of using another clone of my original (legacy) Windows 10 HDD to boot as a single drive on the computer, wait for the Windows drivers to install and... it's done. I reinstalled the Mojave disks and it's AOK now.