Pretty sure you will need a x8 slot.
You will also need a 10GbE link partner - something on the other end that can communicate at 10Gbps. Last I checked, any 10GbE Copper switches were several thousand dollars. Something to consider.
Hi Jkurts -
10GbE is a lot of I/O for any system, but with the new i7-based machines you should be able to actually utilize most of a 10GbE Ethernet card. Intel makes 10GbE NICs with a PCIe x8 interface (not x16). Obviously you can put the NIC in a x16 slot, but you should be vigilant to make sure that BIOS on your machine does not limit non-graphics devices in the x16 PCIe slots (some BIOS code limits non-graphic devices to a PCIe x1 bandwidth).
Thanks guys. Good to know about the BIOS limiting PCIe bus speed for non-graphic cards.
Say I do have a 10G switch/hub (maybe in year 2020), and I do file transfers between my computers. Would today's hard-drive even capable of read/write at 10Gbps? Maybe solid-state ones? If it is not, then may need a lot of buffering. Would the next bottleneck then be between CPU and Memory banks? Would I need the latest and greatest DDR3-2000MHz?
Anyway, just curious thoughts running across my mind. Thanks for the feedback.