R310 and VT-d

Hi Everyone,
We have 2 DELL R310 servers which we want to use to install a new broadband management app- on a KVM hypervisor.

One of the requirements is that the hardware should support VT-d. The Tech guide for the DELL R310 does state that the chipset supports VT-d, but I have looked everywhere in the BIOS and LCC, but I just cannot locate the option to enable VT-d. (I did enable VT-x)

I also upgraded the various firmware to the latest, but I still cannot find this option. Does this mean, it's enabled automatically?

Thank you for any assistance!
--- Helmuth Kisting