XPS 8950, won't detect Seagate X18 18TB internal HD

These are available with two different interfaces -- SATA or SAS.  Only the former will work -- which version did you buy?

SATA -- I always buy this format.

Is BIOS set to RAID or AHCI? Don't change that setting, just see how it's set. 

the new 18 TB hdd would not show up in Windows Explorer until you initialize it.  did you use disk management to look for unallocated new hdd?

I'm actually using the AHCI/NVME mode. Thanks all for replying.

I don't understand why I can use the 14TB HD, but not this 18TB.

make sure when you swap hdd, both sata power and data cables are securely connected.  when in doubt of cable motherboard connection, swap back the old 8TB hdd to check again.

can you upload your bios screen shot that shows the current 8 TB and 14 TB on sata ports?  if they are shown there, when you replace the 8TB with the new 18 TB, does sata port show none?

@redxps630​ it doesn't show up in Disk Mgmt. That's why I'm posting the question here.

Re: I bought two of the same drives, but my system doesn’t recognize either of them. 

do you have any old desktop to test these hdd?  at this point can not r/o two duds.

Are you swapping in a new 18T drive in place of one of the others, or adding it as an extra drive? If as new drive, are you sure the new SATA data cable is good? You could test it on  one of the drives that's seen and usable.

Have you tried clearing BIOS?

1. Reboot and start tapping F2 when you see the Dell splash screen to open BIOS setup
2. Copy down all current BIOS settings, to be safe
3. Power off, unplug power cord from rear of PC
4. Press/hold power button for ~15 sec
5. Open case and remove motherboard battery (check Service Manual for details)
6. Press/hold power button for ~30 sec
7. Install 18T drive
8. Reinstall battery (Time for fresh CR2032 3-volt coin cell battery?)
9. Close up and connect mouse, monitor and keyboard
10. Reboot

Is the new drive seen now?

I guess both hard drives are faulty. How is that possible?

I just received another hard drive, slightly smaller at 16TB, and there are no issues at all.

Thank you, everyone, for your help.

Re: I guess both hard drives are faulty. How is that possible?

it happens. both from same bad batch