I have a 2009 MBP 2.53 Core 2 Duo... Original HDD failed so I bought a Saumsung 840 250gb, I cannot get the mac to read it. So I returned it and bought a OWC Mercury Electra 3G 240gb drive and I get the same thing. I hooked up a 120gb Intel 520 Series and it sees it right away, along with all regular platter drives. What can I do? I reset the pram or whatever you like to call it. These larger ssds just won't show up in disk utility, but if I use a usb adapter of course they work. The drives are good! Possible firmware issue on the MBP? SATA cable? Please help!