Intel Processors based on the consumer platforms (Core i5/i7, Xeon E3) do NOT support ACS in the Processor integrated PCIe Controller. If you were to use a SR-IOV NIC, Linux by default will build the IOMMU Groups with both the NIC PF and VFs as part of the same group (Even if it is a single card and you don't bifurcate to 8x/8x), which means that unless you use the ACS patch (Considered an unsafe hack), you can't passthrough a NIC VF to a VM using QEMU (Other Hypervisors should present similar issues). You can technically get full functionally if you use Chipset PCIe Slots since they do support ACS, at the cost of latency and perhaps bandwidth since Chipset slots with 4 lanes are rare (I never saw more than 4 lanes in a Chipset slot and I don't know if it is technically possible).
Basically, you need a LGA 2011/2011-3/2066 platform if you want full features. You also get APICv. Core i7 HED works, but avoid Skylake-X, that while I don't recall seeing proof that they don't have ACS/APICv support in LGA 2066 but I wouldn't risk it anyways since logic says they don't support it since its the same silicon.
