Enable Vt-d from bios

Hi,

I would know if I can enable Vt-d feature in a R720 poweredge server from bios.
It seems that all hw supports Vt-d, but I don't see specific option in bios.

server: poweredge r720
chipset: Intel c600 family
CPU:  Intel(R) Xeon(R) E5-2670

BIOS Information
Vendor: Dell Inc.
Version: 1.6.0
Release Date: 03/07/2013

Thanks,

Pietro