I have a 2010 MBP i5 running 10.6.8 with 8gb of ram. I recently swapped out the hd for a Samsung 850 EVO and am having massive problems: With the drive running internally I get slow downs and crashes (gray screen, computer freezing) and the access speed of files on the drive are much worse than with the original 5400rpm drive. On the other hand it runs smoothly enough when it's booted as an external and running using a SATA>usb cable!?!?!? The original drive works fine when internally, certainly doesnt exhibit as slow speeds or any of the crashing/freezing when mounted internally. I have now tried both cloning the original drive (using CCC and SuperDuper) and also reinstalling using my original disks and seeing what happens. Does anyone have any ideas!? Please help! Thanks!