We would like to inform you that only the 3rd Generation Intel(R) Core(TM) i7 Processors are designed to natively support PCI Express* 3.0:
I assure you that if you buy ANY i7 CPU LGA 2011 & that board you will have your PCI-E running at Gen 3.0
Intel in their infinite wisdom "don't ask me why" have disabled the PCI-E Gen 3.0 on their boards. Albeit, there is a way to workaround this but, you won't be needing it; since your board supports the Gen 3.0 out of the box.
Surely to utilize the 3.0 technology you need a video card that supports the PCI-E 3.0 "eg. Nvidia 680 or 670".
I don't know which ATI models run on Gen. 3, I only use Nvidia.
So don't get lost into the technical details & I assure you that it will run on PCI-E 3.0 as long as you get a compatible PCI-E card that is designed to run in Gen 3
"i7-3820", is more than enough for any gaming rig or video editing. Unless you multi task like crazy the CPU I mention is more than enough.
Once more every I7 CPU LGA 2011 supports Gen. 3