AHCI is preferred for SSD because it has support for TRIM which is a way that Windows manages deleted files on the SSD. Try different SATA ports on the motherboard and if you have any other HDDs, disconnect those and see. Are you trying to use the SSD as an OS drive?
I think you need to change to ahci BEFORE installing Windows. If you play with this BIOS settings afterwards Windows might not recognize the drive and you might get a blue screen on reboot it is a common issue.