I just upgraded my MacPro 3,1 with a Samsung 860 EVO SSD 1TB. I am running High Sierra. I formated the SDD using HFS+ and then cloned it from my old hard drive using Disk Utility. I did turn on TRIM. I have turned on FileVault and has finished encrypting the drive. The EVO is installed in a SATA II drive bay. I realize I will only get SATA II speeds. The system boots up much faster than with the old disk drive. My system is running but very slow. The beach ball spins between nearly every mouse click. Way slower than the old disk drive ever was. Anyone have any ideas for me? From reading these forums I would expect a small increase in disk access speed. Thanks.