X5660 Processor supports VT-d technology?.
In this linkhttp://ark.intel.com/Product.aspx?id=47920does not appear to support it.
You might want to verify it is enabled in the BIOS.
If it is and you are still unable to see it, then make sure you mention the VMM.
The Intel Xeon Processor X5660 link is here:
(Your link is for X5670.)
VT-d is a chipset feature, so it is not listed on this product page. If you look at the associated chipset product for the platformyou should see it.
The intention of the combined platform is to support the feature. (Among other reasons, TXT requires it.)
Oops, I misread the question and thought it was about the unavailability of VT-d in the software.David's explanation pretty much captures it. The BIOS issue isa rather common issue which frequently arises.