Hi all,
I have a very similar problem with my P751ZM. I am trying to upgrade my SM951 256GB to a PM951 512GB I got from an AlienWare, but nothing seems to work.
The SM951 is visible in the BIOS, Windows runs with no problem etc. The PM951 is visible from the Windows 10 installer, but not from the BIOS. I could install Windows on it, but it's still not visible in the BIOS, no matter how I configure it (UEFI or not, Secure Boot or not, CSM or not etc.).
I just updated the BIOS from the manufacturer website XMG.GG (my laptop is a XMG U505), just to say that updating the BIOS isn't a solution either.
Here's a dump of the current BIOS, I would really appreciate if someone could help...
https://www.dropbox.com/s/wngqknch1vm846s/results.rar?dl=0
Thanks!