Just had one of the two new 1.5 TB disks bought for testing show up as 500 GB disk in BIOS and Windows – motherboard was GigaByte, which seems to have had same issue with Hitachi disks before.
The solution is to try to use Seagate Tools (DOS) to set new native Max setting. This action actually failed (or so the tool reported) however after short test was run it became clear it treated the disk as 1.5 TB. After reboot the disk was correctly recognised by BIOS.
If you buy one of those disks make sure you upgrade your firmware (SD17 to SD19, and some other CC1H – you need get the right one for your disk as they use different platters) – you can do that by going to chat with Seagate support, they answered pretty quickly however it then gone to hell as the ISO file they gave me was shown as broken and burning it only resulted in README.txt file shown. One hour later they cut me off as they claimed it was all fine – it turns out they were right and booting that disk worked! However they had no clue that this was non-standard ISO, probably intentional to avoid people copying the firmware data.
Don’t use quick format on those disks – there are serious questions on their quality (that’s why they must be so cheap), don’t trust anywhere near important data to those – I know I wouldn’t, but they might be okay for temporary files usage where failure can be tolerated (barely). Seagate really deserves to be seriously slapped for terrible customer experience (you can’t easily upgrade firmware) and having such serious quality issues in the first place with top of the line hard drives.