Newer PC wont recognise my old SSD drive?

cx6

***IF*** it is connected as a secondary drive then it may not be recognised as a bootable drive.

If you then boot from supplied the boot drive into Windows you may see the secondary drive with an assigned drive letter eg

If it is not, then you could look into disk management and assign it a drive letter.

All this presuming the drive shows up in BIOS setup

googler

googler said:

If you're connecting the old SSD as a secondary drive, and you already have a boot drive in the PC as supplied, then I experienced the same symptom recently; I found the solution buried in an obscure Windows forum, and will post it here when I find it again...

The solution was to run the Memory Diagnostic tool. 

I had the new PC, with a single drive, with Win 10 installed, and wanted to add secondary drive. It showed up in BIOS, but Disk Mgt and File Explorer did not 'see' it. 

I found the solution, as I said, in some obscure forum or other (EDIT - now shown below), and then followed the instructions here;

https://www.c-sharpcorner.com/article/windows-10-memory-diagnostic-tool/

I know, it doesn't sound like it's connected, but .... it worked.  

User Chris_166 put me on to this, in

https://forums.tomshardware.com/threads/hdd-shows-up-in-bios-but-not-in-device-manager.1524311/

Two or three folk report success therein.