XPS 8940, NVMe M.2 drive on PCIe 4x expansion card, does not work

@DroZ3 Have you tried booting using the F12 Boot Menu to select the 970? The problem could be either that the OS is still on the WD or that you cannot boot from an expansion card. If you are successful booting from the 970 using F12 you should reinitialize the WD to get rid of the OS and boot/EFI partition. 

@Vic384 I formatted the WD in NTFS to remove the OS. Let me reboot to confirm the boot sequence.

@Vic384 

By the way, goal is to continu booting from 970 and use WD as additional storage.

@DroZ3 Are you successful using F12 to boot from the 970? Until you reinitialize the WD, you will have to use F12 to make sure you boot from the 970.

I think you can reinitialize the WD by using Disk Management, but I like to use DiskPart. Here is how you use DiskPart: https://macrorit.com/partition-magic-manager/initialize-disk-gpt-mbr-from-cmd-diskpart.html

When using DiskPart, make sure you identify the correct drive using the 'list disk' command and make sure you select the correct drive by using the 'select disk' command. 

@DroZ3 I  assume the WD is for additional storage. Formatting will get rid of the OS, but not the other partitions, such as the EFI partition. You may wish to read up on using DiskPart from the Command Prompt. Run Disk Management on the WD and see if other partitions remain.

you are right, I only did a format but forgot to delete the partitions ... duh.

Will do and tell you what happens, probably tomorrow.

You need a disk format not a partition format

CMD as admin 

Diskpart 

List disk 

Assuming that WD is disk 1 

Select disk 1 

Clean 

Now you will have an allocated space in disk management and you can format it as you want. 

@Vic384 I tried F12 to boot from 970, but even after having selected 970 to boot the 8940 would still try to boot 3 times then gave me an error message.

@RoHe before I go forward with your procedure :

1- What do I gain and what do I lose if I switch from RAID to ACHI ?

2- Will this affect any of my 2 others disks already installed (1TB 970 on motherboard and 2TB SSD in expansion rack.

3- Is there a reason Dell has his setting at RAID out of the box ?

Thanks for the help guys.

@DroZ3 Is there an option to make Windows Boot Manager the first option in the Boot Sequence instead of what you currently have (UEFI Samsung SSD 970 EVO Plus 1TB)? If there is a Windows Boot Manager option, try that.

@Vic384 ... Not sure I follow.

If the SN 720 is a SATA M2 could be the reason it DOES NOT WORK with a PCI-E X4 card. The other reason could be that your system does not support PCI-E bifrucation and therefore multiple M2 drives is not possible without a controller.

M2 is a socket not a drive specification.

cards with B & M key are SATA.

cards with A & E key are Wifi.

when you put the M2 drive in a usb dock it can be CLEANED with diskpart removing all partitions.

If f2 Sata operation is set to AHCI then M2 drives work.  IF it is set to IRRT RAID optane mode M2 drives will not be seen by diskmgmt.msc.

@DroZ3 In the BIOS you showed the first boot option as 'UEFI Samsung SSD 970 EVO Plus 1TB'. I wonder if you can change that option to Windows Boot Manager. I don't have an XPS 8940, so I don't know what the options are. In previous XPS models, the first boot option is usually Windows Boot Manager, that way if you insert a bootable USB or CD, the Windows Boot Manager will show the available boot devices in the F12 Boot Menu and you don't have to change the boot sequence in order to boot.

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@DroZ3 wrote:

@Vic384 I tried F12 to boot from 970, but even after having selected 970 to boot the 8940 would still try to boot 3 times then gave me an error message.

@RoHe before I go forward with your procedure :

1- What do I gain and what do I lose if I switch from RAID to ACHI ?

2- Will this affect any of my 2 others disks already installed (1TB 970 on motherboard and 2TB SSD in expansion rack.

3- Is there a reason Dell has his setting at RAID out of the box ?

Thanks for the help guys.

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1. You won't lose anything if you change BIOS to AHCI. It might (help) solve the problem if  Windows Boot Manager thinks the SSD in the x4 adapter is part of a RAID array, which causes it to fail to boot.
   
   
2. Should have no effect on any other drives already installed since they're not in RAID arrays. RAID uses different drivers. So you do have change that SATA setting in the right way so AHCI drivers get installed into the OS on the SSD in the motherboard's M.2 slot. 
   
   
3. Good question. It does make for one less manufacturing option because RAID can be used whether there's no array or when there is a RAID array, for example, between a HDD and an Intel Optane module that's used as cache to enhance HDD performance. If they defaulted to SATA Mode set to AHCI, they'd need to change that setting prior to setting up a system for RAID, and they'd need a different OS image that has the RAID drivers installed

@speedstep The X)S desktop bill of material was calling for a 256gb NVMe M.2, I have to assume the WD SSD is NVMe, unless Dell did a bait and switch, but I doubt it.
You said above the "cards with B&M key are SATA, but the image below shows a B&M key NVMe ... I am confused.

I formatted the WD at work with an M key USB adaptor but I forgot to delete the partition(s), if s), so the WD may not be as clean as I was thinking. I may have to go back at the office and use my IT Manager M key adaptor as I don't have one.

Gee, all of that for 256gb ... LOL.