XPS 9510 second NVME drive

If you change to AHCI in the BIOS, you will have to reinstall Windows. That second drive is part of the RAID setup and will not appear as a separate drive, it will be a mirror of the first drive. This forum thread should help.

So what you're saying is the default setup of my Dell XPS 9510 does not allow me to add a second NVME drive to the available slot without reinstalling Windows? That seems wrong. Why would they do that?

I think that should not be the case -- a drive won't automatically be added to a RAID 0 array without user intervention.  Leave the system in IRST mode and go into setup (F2 at powerup).  The drives should both show there.  If they do, it should then be a simple matter of partitioning and formatting the new drive under Windows using the disc administrator snap-in.

You can change from IRST to AHCI without reinstalling Windows, but it should not be required to do so unless that's what you want to do (for example, disc managing utilities from Samsung (Magician) or WD (Dashboard), etc. won't see the drive if it's in IRST mode.

If you do want to change modes without reinstalling see below (and by all means, prepare and verify a full system image backup before doing so).

https://support.thinkcritical.com/kb/articles/switch-windows-10-from-raid-ide-to-ahci

Is there any other drive connected to the system such as a flash drive?  The followup to  that  would be, what happens if you change the drive letter to something other than d: (such as f:)?

To clarify...the drive is visible in the bios in irst mode. I partitioned it in Windows as a d drive.

Now, however, when I reboot it is only visible for a few minutes (as the d drive) and then disappears. Windows can't see it at all and can't see it within disk management. 

I do not have a flash drive or anything like that plugged in. I can't get the new drive to be visible long enough now in Windows on reboot now to change anything. 

I reached out to adata but no response from them. I don't know who is to blame but this is quite annoying. 

After trying different ways to solve that problem I finally found the root of the problem. And that is not in RAID drive mode, power management, drive firmware or overheat. But heatsink will help, because if you look at the back plate it place where NVME drive located, you found conductive sponge. And this sponge short circuit some components on NVME drive when you push a bit harder to back side of the laptop. And that looks "randomly happened" and drive can diapear before OS boot or after. To avoid this install heatsink or atleast capton tape on the sponge/drive.