The NEC Corporation ExpEther 40G I/O Expansion Unit Quad Slot.

The technology innovation of ExpEther expands the power of the PCI Express switch beyond the computer chassis via Ethernet without modification of existing hardware and software. ExpEther 40G devices delivers a compelling solution for real-time Big Data processing and other data center workload acceleration. It does so by enabling the connection of GPGPU, NVMe SSD, or FPGA-based accelerators via an Ethernet connection. Please visit the ExpEther consortium 

These I/O Expansion Unit are connected to the host server via a standard Ethernet by the ExpEther 40G Host-Bus adapter (N8104-165). Please see the material of this Host-Bus adapter.