I am sure the RMA closed if it was created 2 years ago. Probably best to contact sandisk support and get a new one.
for a boot drive you cant change from IDE to AHCI with out making some changes to the registry. IDE and AHCI use different drivers so if you change the BIOS setting the OS will not boot from the drive. This should not make any difference for detection in the BIOS though so if it is not detected in the BIOS it would need to be replaced.
