PCIe v2.0 (5.0GT/s)

Intel 82599ES SR2 is a PCI Express v2.0 dual-port network interface card that supports 10 Gigabit Ethernet connections through SFP+ transceivers and is used in data centers.

Intel 82599EN SR1 is a PCI Express x8 Fiber Optic Ethernet Network Interface Card with a single port and supports 10 Gigabit NIC 1 SFP+ connectivity.