SOLVED : Samsung EVO 850 SSD SATA III working in Optical Drive now.
MacBook Pro (15-inch, Early 2011) - 2.2 GHz Intel Core i7.
I have SSD as main drive and a HDD in "Optical Drive", But it was taking too much battery/ too much noise. I put a new Samsung 860 EVO 500GB SATA III SSD in optical...