WangGang :
My laptop can detect the drive in BIOS and windows, but the drive won't show up in boot menu, with or without CSM enabled. What's going on?
If system is set to boot into UEFI mode, only devices with bootloader present will show up in boot menu.
If there's no OS installed on SSD, it will not show up.
Also it may be necessary to specify that M.2 has to operate in sata mode in BIOS.