Any reason my pc can't support 6TB drives?

I am wanting to put 2 × 6TB into a home NAS and have a 256gb included nvme ssd as its boot drive. The system I'm using is a dell precision 3620 and on the spec sheet it says it only supports upto 2×4TB drives. Is this just a partitioning thing or is it physically unable to support higher drives.

The system is an i7 7700, 32gb rams that I intend to use for a home media server