Seagate 3TB Only showing as 746gb

[SLiiDE]

Hey all, Recently bought myself a new 3TB Hard drive to replace my current one. I plan to create a Disk image of my current hard drive and then put it onto my new one so i don't have to reinstall everything

Now, i put the new drive into my external dock (Which does support all types of sata drives of any size) and opened up Computer Management. Under storage the drive is only listed as 746gb. I tried initializing it and formatting it to GPT but it still says 746gb.

Anyone got any ideas?

PC Specs:
AMD FX-4100
Asus M5a78-m USB3 Mobo
Windows 7 Pro 64bit