Hello, I am in the process of building an HTPC. I got it to boot of an ssd and installed everything I need and it is a great stable computer. I then tried to shell an external 4tb wd green drive and hook it up internal via SATA. When I did so it showed up in the BIOS and in disk management (but as unallocated/unformated space), but not in my computer. I was finally able to get it to show up in my computer, but only as a drive letter when it asks you to format it before you can access it (which I really don't want to do). I used the usb adapter that was inside the drive enclosure to ensure the data wasn't corrupted somehow and it came right up in computer with all the files I had on it. What would make the drive not show up when internal SATA, but perfectly normal via usb external.