Xps 8900 and Evo 850 will not see 6tb WD black

[Coup27]

AFAIK there won't be any negative to running two single drives in RAID but that's not the point, it should work in AHCI. It's stuff like this which annoy me with OEM machines. Always these type of random niggles which just shouldn't happen and don't happen on whiteboxes.

 

[corkyg]

Admin Tools/Comp Mgt/Disk Mgt and see if it is a drive letter problem. If, for some reason, it has the same letter that is already assigned elsewhere, it won't be seen.

 

[Elixer]

Admin Tools/Comp Mgt/Disk Mgt and see if it is a drive letter problem. If, for some reason, it has the same letter that is already assigned elsewhere, it won't be seen.

That isn't possible, drive letters aren't hard coded like that.
UUID can be in conflict if you clone it, but, that wouldn't make the drive not be seen in windows.