Precision T7500 GPT? EFI? Raid-Config over 2TB

Hello,

When I configure a workstation T7500 you can config this option: "Raid Config over 2TB" RAID0 Stripping. A friend of mine orderd this machine with 4,5 TB (3x 1,5 TB) . But it seems that the Workstation can't handle the 4,5 TB, because the BIOS has no EFI-Option (for booting over 2TB). So he can build this raid-array with full capacity, but isn't able to install an operating system on it. This option doesn't makes any sense. What do you think?

The delivery situation (pre-installation from dell): They configure a RAID0 of 2x1,5TB, so 1TB is simply lost and the third HDD is non-raid.