My vertex 4 has firmware version 1.5, it is detected at a negotiated link speed of 6Gb/s in my early 2011 15.4" Macbook Pro's optical drive SATA slot. I have tried installing both Lion and Mountain Lion on the drive using USB drives that have both successfully installed the OSs on other computers. It repeatedly fails after it completes "Preparing for Installation". The only message I see is "Installation failed, please try again." In addition to this, the drive is not recognized AT ALL in the normal HDD SATA slot, only in the optical bay SATA slot. In the optical SATA slot the drive is recognized and shows up just like a normal connected drive in finder. I can move files to and from it no problem, all indications suggest it is working perfectly. I cannot however install Mountain Lion to it without failing. I am currently typing booting from my regular HDD in the normal HDD SATA port (so I know that connection works) and the Vertex 4 in the optical slot. I have formatted the drive several times and it will not work. I also attached the Vertex 4 through USB via an external SATA adapter. Mountain Lion installed to the drive no-problem this way. I have since re-placed the Vertex 4 in the main and optical SATA ports but it will not boot to this drive or be recognized/seen at all in the main SATA slot. I can select it at startup but it just hangs and eventually boots into my normal HDD. I have reset SMC, PRAM, tried every combination of SSD and/or HDD drive locations, and done what I would consider my due diligence as someone who is familar with Macs and computers in general. What should I do? Thank you all very much for the help in advance.