Moving a (working) bootcamp Win 10 partition to an older iMac

“In OP, you mention AMD Radeon HD 6750M graphics driver, which is different. Can you Identify your iMac model - Apple Support exactly? There may be a possible solution, depending on your answer.”

Apologies; it is the older iMac 11,2 (21.5-inch, Mid 2010) with the 4670 GPU, so a possible solution is welcome. The last machine I successfully installed W10 on was the later mid 2011 model.

"Take a look at Boot Camp: iMac displays a black screen during installation of Windows 7 - Apple Support. This provides a W7/W8.1 driver, not a W10 driver. You may be able to install it on W10, and may need to disable signature enforcement."

Once again, many thanks for the tip, but I managed to solve the problem another way. I downloaded the Bootcamp driver software while booted into macOS High Sierra on the iMac in question. I then booted into Win10 on the Bootcamp partition and tried running the drivers' setup.exe. I got as far as 'This version of Bootcamp requires Windows 7 to run' . I next directly ran the .exe for the required ATI video driver instead but installed the Catalyst software on the Windows desktop rather than into /Program Files directory, as I had encountered a fatal error and had to reboot into Windows when installing there before. This time, I was offered a list of drivers to install including the one necessary for native graphics support and it worked first time. The screen resolution switched automatically to 1920 x 1080 and that was that. I must say that Win 10 runs very smoothly on this old Mac, for my needs at least!

I know it’s not natively supported but it should be possible to manually install the graphics driver from the right boot camp support package. You can certainly install W10 on this 2011 iMac using a W10 iso burned on a DVD with the BC support software on a USB drive. I know, because I’ve done it before! The problem here is a W10 BC installation moved to an older Mac. I doubt a Windows update will fix it but I’ll try it.

Thanks for the tips Loner T. You wrote 'To get W10 on 2011 and older Macs, the unofficial method is to first install W7/W8.1 including BC5.x drivers, and ensure proper functionality, and then run an in-place (not BC Assistant and/or Winclone) W10 upgrade, which 'grand-fathers' the installed W7/W8.1 drivers'

I would normally have done that of course, but I have successfully installed W10 directly on an identical older iMac beforehand, essentially following the guidance here https://www.youtube.com/watch?v=KJThhtD6ycs. My problem is the incompatibility between the driver installed for running on a Retina 27" iMac and the ancient Radeon graphics chip in the 2011 iMac. Everything else is working just fine.

"I assume this is without Winclone? I have not had a chance to look at the Video".

Yes, vanilla install using a DVD burned Win10 ISO and bootcamp driver support.

"What is the version of the AMD driver on the 'identical' older iMac on which W10 is fully functional? Can you try to install the same on this iMac as well?"

I don't have that installation any longer, unfortunately, but following running msinfo32, system information tells me that the graphics adaptor is the AMD Mobility Radeon HD 4670 (as expected). So Win10 sees the display card OK and I need to install a driver for it that works. The BIOS Mode value is 'legacy'.

Thanks

Done thanks! My next task is to get Virtualbox to boot the Bootcamp install from macOS! A battle for another day.