Hello everyone the problem is in fact the SATA connector at the tip of the cable. It only makes good contact with some HDDs. the fix! is simple. put 2 lines of masking tape on top of the DATA side of the HDD connector, then plug in the ribbon cable and turn on the machine. you will get the apple sign if the HDD has OS on it if its empty boot from cd and check on disk utillity. putting the tape: instruments: masking tape(blue or white), a small flat screw driver, and scissors. put a piece of tape on top of the DATA side or if you want it could go accross the DATA AND POWER, NOTE, ON TOP OF THE PLASTIC AREA, DO NOT PUT TAPE ON THE PINS SIDE, I REPEAT DO NOT PUT THE TAPE ON WHERE THE PINS MAKE CONTACT. THE TAPE GOES ON THE UPPER SIDE THAT IS ONLY PLASTIC. cut tape very close to the edge. make the division between DATA AND POWER on the tape and plug into ribbon cable. ENJOY.