WD Green 4TB shows as 1.63TB

The basics:

I’m using a Macbook Air running Windows 7 SP1 via BootCamp.

I bought a WD Green 4TB desktop drive and placed in an external WD MyBook enclosure that I’d been previously using with a 500gb drive.

I formatted the new 4TB drive using WD’s windows drive formatting tool.

And the drive only shows as 1.63TB total. No other space or partitions or anything.

I have tried converting the disk to GPT but that is not an option in any disk management system I have tried. That option is always greyed out.

There is no other partion to delete or remove or reduce in size.

I googled this for hours last night and found no solutions.

I’d appreciate any help.

Hi Eddie, note that replacing the internal drive is not supported. To troubleshoot the drive, try to connect it directly to a computer motherboard and see if you can access the full capacity.