I have a 2012 Mac Pro running El Capitan 10.11.6. 3.33 GHz 6-Core Intel Xeon with 32 Gig Ram. I have an Apricorn Velocity Duo PCI card with (2) Samsung EVO SSD Drives (which I use one as a boot drive and one as a scratch disk) My (4) Internal Hard Drive Bays until recently had all 1-TB Western Digital SATA Drives and I never had a problem. A few months ago (as a preventative measure), I purchased (4) new internal SATA HGST Deskstar Hard Drives to replace my aging Western Digital drives. Ever since then when I try to play a video in ANY of my players (like Quicktime, VLC, etc.), the video will play smoothly for about maybe 6-7 seconds and then stall and jump forward several frame to catch up? It is doing this will ALL my videos in ALL my players when I try to play from ANY of these new HGST Deskstar drives! If I copy one of the videos to any of my other drives (Internal SSD or even external Firewire drives everything works smoothly as expected. So what is the deal with these new HGST Drives??? Is this a know issue? Is there a fix? This is what I purchased: https://www.bhphotovideo.com/c/sear...Search=yes&sts=ma&typedValue=&Top+Nav-Search= If I am not mistaken, they also seem like they are generally slow even for non-video work?