Migrating Windows 7 from BIOS-MBR to BIOS+GPT
Solution 1:
This answer summarizes the comments on the post in a more orderly manner.
While no answer was received for making Grub work in this context, I did find out that the BIOS of the motherboard in question, MOPNV10J, does support UEFI, as answered (link) by an Intel person called Dan.
With UEFI support, the 3TB disk can be formatted as GPT and the entire disk then becomes addressable.
Since the poster's BIOS does not support UEFI, the question now becomes how to update it to the latest Version 0542.
It turns out that updating to that version needs to be done in two steps:
- Update the BIOS to Version 0400
- Update the BIOS to Version 0542
Before starting, ensure first that you have the installation media for your current BIOS version, called "Recovery BIOS Update" in the release notes. Otherwise a botched BIOS update can brick the computer.