Today when I opened my laptop the screen pixelated and blacked out. I held down the power button and during the restart it froze just after the Apple logo disappeared. My initial thought, along with the local computer shop, was the hard drive had gone bad. I installed a Samsung 840 Pro earlier this year which seemed odd for it to fail this quickly, but it was an explainable diagnosis. They installed a new Samsung 840EVO and I went on my way. My plan to reinstall OSX was to boot from the original HDD, which was running perfectly before I removed it and just last week from an enclosure, and install 10.10 from a local backup. When I connected the HDD the computer booted and froze at the same place just after the apple logo disappeared. For good measure I connected the recent SSD (840 Pro) to a running MBP and it loaded instantly with access to all my files. This leads me to believe the SSD is fine and the problem is the computer itself. Here's a list of things I've tried to get the computer running on the original HDD. Not in this order. - reset the PRAM - boot into single user mode - boot into safe mode - verbose mode (also with safe mode) Aside from resetting the PRAM nothing has made a difference to the boot up. It hangs on the grey screen and nothing is outputted whe I boot with verbose mode. Is my computer a goner? Is there something else I should try? I tried to boot into recoveryfrom the HDD and the screen turned blue with vertical lines (top to bottom). What could this mean?