Winclone 9 and 2015 5k iMac with dual internal SSDs

Hi everyone - as a lockdown project, I took a 5k iMac from 2015, opened it up, and replaced the fusion drive with an NVME SSD to run Big Sur on, and a Sata SSD to run Boot Camp on.

Unfortunately, I didn’t realise until after I closed the machine back up that Boot Camp Assistant doesn’t work if you have two internal drives.

I’m now working on a workaround and thought I’d start by creating an image of the Boot Camp volume on my Macbook Pro, to then copy across onto the Sata SSD.

All went well until I restarted my computer and tried to log into the Boot Camp drive. Instead of one Boot Camp drive, it detected two, and when I tried to select either one, the computer screen went black, spun up for fans for a while, then turned off.

I suspect this is a driver issue. Does anyone have any suggestions on what to do?


I doubt it is a driver issue since Windows drivers are not loaded at this point. It is most likely the boot config on the EFI partition (usually slice 1 on the drive).


Thank you very much for that insight - any suggestions how to resolve that? I’ve tried booting from a windows iso USB but that didn’t work either.