Hi Friends,
I'll try to be as specific as I can.

My rig: (currently running under Win7 Pro SP1 64 bits)
MB: Rampage V Extreme/U3.1 with Bios: 3701
CPU: i7-5960X
32 Gb memory: 4x8Gb modules Corsair CMK16GX4M2B3000C15
current SSD: Samsung 850 EVO 500Gb (contains Win7 Pro x64)
HDD: WD Black Sata III 3Tb (contains only my own data and software)
GPU: GTX 980Ti 6GB
cooling: Corsair H100i GTX
PSU: Corsair RM750

I wish to install Windows 10 Pro on my PC with a dual boot W10 / W7.

So , given your recommendations (see topic 'SSD compatibility with R5E/u3.1' of 11-17-2018 ), I bought a Samsung 970 Pro M.2 NVMe which I installed in the MB M.2 socket.
I wish to install W10 Pro on this new M.2 drive, and have a dual boot with W7 installed on the older SSD( the 850 EVO)
Initially the 970 was not recognized by Win7, (unknown PCI device in device manager) until I installed the Samsung NVMe driver version 3.0.
Under Win7 in device manager, I can now see 'Samsung NVMe Controller' in 'Storage Controllers', driver version is 3.0.0.1802.
I also see the drive in 'Disk Drives', it is called 'NVMe Samsung SSD 970 SCSI Disk Device'.

I have launched CrystalDiskMark5 on the 970 and got good results (Seq Read: 2753 , Seq Write: 2710)
I also have launched a full Disk Check (still under Win7 of course) on this drive, which found no error.

Windows 10 installation:
I have downloaded Windows 10 from microsoft and have created a bootable USB flash drive. I can boot fine from this flash drive.
The problem I face is that the installation of WIndows 10 on the 970 crashes.
To be more specific: the installation randomly crashes (BSOD or hang) during phase 2 of the installation: 'Getting files ready for installation'
When I get a BSOD, the error is often 'WHEA Uncorrectable error', but can be 'Kernel security Check' , 'Page fault in non paged area', or others.
The crash happens randomly between 0% and 65% of this phase.

The issue is that I do not know which settings I must put in the Bios when booting from the flash drive.
I have set 'Onboard Devices Configuration'/'PCIEx8 and M.2 Configuration' to M.2 instead of Auto

I've read tens and tens of posts on installing W10 on M.2 NVMe, they are often contradictoty.
For example, what about the CSM ? disable or set 'UEFI Driver first' in the PCIe-Ex Storage section' ?
Secure boot menu:
- 'Windows UEFI Mode' or 'Other OS' ?
- 'Key Management': Clear secure boot keys ?

Should I disconnect all the other drives (850 EVO, HDD and CDR/W) before boot and install?

The (failed) installations have created 3 partitions on the 970 (displayed by disk manager of Win7):
a 499 Mb one : Healthy (Recovery Partition)
a 100 Mb one : Healthy (EFI System Partition)
a 953.27 Mb one: NTFS Healthy (Primary Partition)

I'm pretty stuck with this crashing installation ...

Can you please give me some help / advice ?
Thank you