In the BIOS settings go to the ADVANCED tab and change to AHCI there.
If you do this in the MAIN tab it woun’t work since you are altering the controller of the SATA 1 & 2 devices connected on a different chipset (e.g. DVD and other optical drives).
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> Congrats on finding your own solution.
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> I still do not know wshat it means that an OS “sees” a drive.
Roughly: the OS will know whatever controllers it has attached
by “quering” the PCI bus - devices that have reported in as “disk
controllers” or “host bus adapter” (IDE, SATA, SCSI, FC etc) will
subsequently be queried to find out which devices they have attached.
If the communication fails somewhere along the line, the OS will
not “see” the drive.