I decided finally to use the modded BIOS from [OFFER] Gigabyte GA-Z77X-UD3H NVMe mod and this works without any problems. My NVMe is a Samsung 980 500 GB and I used the Samsung Data Migration to clone my current SATA SSD OS Drive to it without any issues. They do say this:
Can I move data from an HDD or SATA SSD to a Samsung NVMe™ M.2 SSD?
Yes. It is possible to clone a SATA HDD or SATA SSD to an NVMe™ SSD. Samsung, however, recommends performing a “clean install” of the OS and later transferring the desired non-executable files.
Because the registry information needed for NVMe™ SSDs is different from those of SATA HDDs or SSDs, a clean install helps to avoid unnecessary compatibility and performance issues that may arise from simply cloning a storage device.
But since my old system disk is still in the system (and I do regular bcakups as well) I am prepared to try this rather than having to re-install (and configure) the many different programs I use.
I hope this helps others.
Tony J