Just had a few more thoughts 
Can/have you tried other sata ports?on a different controller if the mobo has it
Also have you used a different sata cable to eliminate that?
Finally that mobo has a dual bios,have you tried to boot from the other bios?

Can/have you tried other sata ports?on a different controller if the mobo has it
Also have you used a different sata cable to eliminate that?
Finally that mobo has a dual bios,have you tried to boot from the other bios?