I think if your external HDD uses 4KByte native sectors (4Kn) instead of 512Byte (512e) it should be possible to utilize more than 2TB as you did not really exceed the 32-bit sector count limit imposed by MBR (which resulted in the 2TB limit). Internal HDD models using 4Kn exist (at least according to disk manufacturers' catalogs), but it's probably not that common as most search results are about 512e models. Although you can make GPT-formatted disks usable by using Windows Server 2003's disk.sys, it does not work around the capacity limit if the BIOS, the SATA controller, or its driver, can't really handle such. I once made a 3TB GPT-formatted internal HDD usable on WinXP this way, but it turned out the BIOS/controller couldn't really handle disks more than 2TB and I ended up corrupting a portion of its contents when I wrote stuffs beyond 2TB into that disk. A good indication would be: If a large capacity HDD is showing a capacity less than 2TB in BIOS (e.g. a 3TB HDD shows as ~972GB), it means the BIOS can't handle such a sector count and overflowed when it tried to read and display it. In this case, depending on your SATA controller or its driver, you risk corrupting data when writing beyond 2TB, regardless of operating system. So Hard Disk Sentinel did not warn me out of nowhere about this back then.