I know this issue is somewhat common and there are many fixes over the internet for it. But none worked for me and i do think my case is different than those i've found online. Well, here's the thing. I just bought a 3TB Seagate Barracuda XT to use as a storage unit only ( Windows boots from an SSD). My motherboard is an Asus Sabertooth Z77. When i first set up the drive it showed in the bios as an 801.5GB unit and i thought this could be normal and later when id format it using windows it would show the full 3tb. However when i got to disk manager, Windows only recognized a 746GB drive. So i started googling. I found out that many people have this same issue. But normaly, in those cases, when you get to the disk manager there is a 2.7tb disk that you can only allocate 2TB and the remaining 746GB stay unused thanks to some partition limitation. So to solve this problem you must change your disk to a GPT type and it should work. However in my case, when i change the disk to GPT, the drive capacity actually shrinks to ~733GB. I've tried installing seagate disk manager, intel RST and other software solutions but nothing worked. So i began to think that the problem was something to do with the BIOS/motherboard since all these fixes show a striped 2.7TB in windows and not only a 746GB drive . Plus, they always say that your BIOS has to correctly recognize the drive first, which is not happening here. So i tried updating the BIOS, i changed every combination of settings in the bios regarding boot, SATA configuration (i enabled all UEFI settings, SATA behavior, secure boot, turned on/off the legacy boot) and even tested the disk in every sata port available in my motherboard (there are two storage controllers in this motherboard) . Nothing worked, the drive still showed up as a 801.5GB drive. So, basically, i ran out of ideas. Any help is deeply appreciated! Thanks!