Making the assumption that GPartEd did the partition table work (10-15 minutes), I've got nothing else to offer to resurrect you're h/d to 3tb.
If nobody else comes on board to try to fix this, RMA it. When you get the replacement, run Gparted to get the GPT; then reboot and initialize it & format it in Disk Management.
By the way, you never answered Doc Brown's question about your BIOS seeing the 3tb as 3tb when you first boot up with it attached to the pc.