Bought a WD Purple internal 3TB SATA HDD.

But when view in Disk Management or other software eg paragon partition manager from Windows 7 32 bit and 64 bit on different computers, i can only see 2TB, the other 1TB is missing. I see from google there should be 1TB unallocated, but I don't see it at all. I tried using various partition and data recovery software but nothing fixed.

Anyone knows solution?