Hi @obvie ,

Would you describe more on your situation?

• What kind of SSD? SATA SSD or m.2?  Encrypting/SED or not? Better provide full brand and model with size.
• How do you deploy Win10? Network or local by USB?
• Is BIOS detected the target hard drive? Any other hard drive attached? If yes, would the other drive detected during Win10 deployment?
• In what step that you noticed about the non-detection? Win10 installation screen do not show the target hard drive? Or target drive shown could not be selected with alert like "Windows cannot be installed to this disk. Your computer hardware may not support booting to this disk"?

1. Sata SSD 512GB

2.deploying via network, also tried restoring an image via dell image assist.

3.yes can see it in bios, yes another 4 TB hard drive SATA, no.

4.No bootable device found

Was the SSD formatted?

Also, for the best and timely service on your new or in warranty Dell products, please contact Dell Support direct using the "Contact Support" link below this post.

Hi @obvie ,

It's more on Windows network deployment issue than Dell hardware problem.

You may refer to this thread regarding similar problem when SCCM network deploy Win10 to some Dell machines. Several points highlighted in discussion may help you on further diagnostic, for example,

• Include necessary SATA controller driver into the boot image
• Locate exact error code when network deployment fail
• Collect logs when deployment fail

we bought 3 of these machines in November 2018, contacted dell with this issue and they sent new hard drives, then they sent motherboards the cpu, and i kept telling them i just not to send parts but to give me setting of send us a technician who can assist. Then they replaced the 2 pc's, we received the 2 new ones in Jan and these are the ones am trying to deploy to, i know if i call dell they will want to replace parts again.

Hello  what i have found  is sometimes   the daughter board in the back of the  SSD NVME CAGE  is to blame  the connections can cause the SSD NVME not to be detected  (  i have replaced  the daughter board in the back of the modular flex bay which great results )   

Also  be careful   model 5820  can have many configurations in the modular flex bays  

ex.    Top bay   1  NVME SSD  conversion   with  bay 2,3,4 have SATA 3 bays  

or  Top two bays  are  NVME   SAS   Conversions

or All four bays  are  NVME SAS CONVERSION 

FYI:   There   are 5 versions  of SAS  CONECTIONS   IN THE BACK OF EACH FLEXY BAY   being the newest   drive bay   SAS  connectors had 6 additional pins  on the SAS   connector  

Hello  more information is needed,  what  SSD   drives are being used  in the   top two modular flex bays ?  usually   NVME  conversions   (  means   SAS   to NVME   also there are 5 versions on the  SAS   connector . ( Version 1-5 |   5 being the latest  which had  6 additional pins on the SAS  connector )  also   chek   all connections  to the ssd in the case that plugs back into the  daughters board in the back of the Flex bay 

FYI   some  version of the Model 5820  Use   2 sata |||    drives in the bottom 2 bays  and   1  NVEM  bay in the top bay area ,  some people are not aware of the  differences in the modular flex bays 

Alos the Mobo  may be the problem  also |  Or the NVME is the problem  

Check to see  if the SSD M.2 NVME is being detected  anywhere  in the Bios  or  Device Configuration  of in the  windows 10   under  device manager and so on  

I hope this helps   

Precision 5820 / 7820 / 7920: Windows 10 Install Fails with NVME Drives | Dell Canada