While my brand new Samsung 840 Pro is on a AHCI activated SATA II port (all I have) Samsung Magician says I am not ("AHCI is disabled for one or more connected SSDs. System must boot into AHCI mode for best performance"). When I try the registry trick the value is already set to 0 and when the system boots my BIOS lists all of the AHCI devices and my SSD is one of them. Any ideas on why Samsung's software says otherwise? Other threads out there have been no help (including the bumped thread - didn't want to hijack a dead thread).
(edit) It also says my current OS does not offer TRIM support yet I enabled it in the command prompt.
(edit) It also says my current OS does not offer TRIM support yet I enabled it in the command prompt.