PC recognizes only 780GB of 3TB WD Red Drive ... Help?

[Abadtk]

   I have a Dell Dimension E520 computer with an Intel G965 Exprees Chipset…It originally came with Windows Vista which I recently upgraded to Windows8.0… I recently bought a WD Red 3 TB NAS Hard Drive: 3.5 Inch, SATA III, 64 MB Cache - WD30EFRX.

My issue it recognizes on 780GB of the 3TB WD RED Drive… any thoughts or suggestions ?

[Hammey]

Hi if you are using it as a boot drive you need to have a UEFI bios. Also the drive has to be formatted as GPT partition to use it as a slave or master.

[Abadtk]

I am not using it as a Boot Drive & I have used GPT to partition it…

When I boot the PC, The hardware recognizes it as a WD 3TB drive,  but immediately afterwards says that it is 780 GB Drive…