Solved Computer Freezes and BSOD after a system upgrade

[BelGarion]

You've narrowed it down to a bad hard drive, despite any positive test results. If it is under warranty, send it back RMA and get a new one.

The difference between a NAS drive and a normal hard drive is Error Recovery Control in the firmware. This has been known to slow down performance in these drives used as a standalone, but otherwise they can work fine as a system drive.

You could try and disable ERC if you can, see if that helps.

Error recovery control - Wikipedia, the free encyclopedia

Already sent back, dropped it off this morning to the shipping carrier the company chose to give me a label for. They're sending me a Seagate that's roughly the same price. Though I might just leave it as it is with the 640gb as the primary and the two 2tb drives as just data storage drives.