Two thoughts based on my personal experience:

1. In my experience, the old trick of copying data to an external drive SATA and then using it without issue in an internal SATA connection doesn’t work with drives that are larger than 2TB in size.

Meaning the format the enclosure uses for data transfer is “oddball” or proprietary partitioning format that won’t allow a simple swap. Or maybe something else is happening? Perhaps it’s being formatted as RAID on a low level for some reason? Don’t know since I never checked this out in depth.

Mind you this is not the case with all external SATA enclosures, but from my casual tests the manufacturer specific enclosures—such as ones from Toshiba and Seagate—a disk formatted in such an enclosure won’t be readable by the system if connected directly.

2. Unclear what motherboard you might be using, but not all SATA connections will allow for drives that are larger than 2TB in size. I would check your system specs to see if that might be the case.

It says the drive has 3 partitions (349,31 GB of RAW data and two unassigned partitions of 1698,68 GB and 746,52 GB). This information is plain wrong, since the drive, when used in the USB enclosure, works as a single NTFS partition (2794,52 GB). How come it’s shown as 3 partitions without filesystem when connected through SATA?!

Is Seagate using some proprietary way of storing the data when using the drive in its provided USB 3.0 enclosure?

Two thoughts based on my personal experience:

1. In my experience, the old trick of copying data to an external SATA drive in an external USB enclosure and then using it without issue with an internal SATA connection doesn’t work with drives that are larger than 2TB in size.

Meaning the format the enclosure uses for data transfer is “oddball” or proprietary partitioning format that won’t allow a simple swap. Or maybe something else is happening? Perhaps it’s being formatted as RAID on a low level for some reason? Maybe even LVM? Don’t know since I never checked this out in depth.

Mind you this is not the case with all external SATA enclosures, but from my casual tests the manufacturer specific enclosures—such as ones from Toshiba and Seagate—a disk formatted in such an enclosure won’t be readable by the system if connected directly.

2. Unclear what motherboard you might be using, but not all SATA connections will allow for drives that are larger than 2TB in size. I would check your system specs to see if that might be the case.