RE: XPS 13 9350 - Samsung PM951 NVMe - RAID to AHCI?
Hello! Yes and no. I am going to assume this SSD didn't come with the computer? If that is correct, Samsung has some software called Magic something that you download and it reworks how windows uses the SSD so your read speeds are much faster during certain IO tasks. As for the BIOS, the RAID option is used for Intel Caching Technology or other purposes and I think Dell just turns it on and leaves it on to make it easier for them. As far as I know, if you switch it to AHCI (which shouldn't make a difference speed wise), your computer will fail to boot.