Optiplex 7440 SCCM (1610) install

Hi

We have had a batch of Optiplex 7440's that I'm trying to install Windows 7 on using SCCM. They come with the PC300 NVMe disk. The install seems to go OK until the reboot and then errors with a Windows Boot Manager message, \windows\system32\winload.exe (0xcoooooof).

I have followed the instructions from the URL's below to inject the drivers and Windows patches into my WIM but none of them seem to work. I'm sure that I'm missing something simple, but can't see it!

www.dell.com/.../requirements-to-install-windows-7-on-m2-drives-in-non-volatile-memory-express--nvme--storage-environments

BIOS is set to UEFI, secure boot off, Legacy enabled. BIOS is also at latest release.

Thanks.