NVIDIA Mellanox ConnectX-5 MCX556M-ECAT-S35A
ConnectX-5 VPI Socket Direct adapter, dual-port EDR IB (100Gb/s) / 100GbE, 2x PCIe 3.0 x8
Host Interface
Socket Direct — 2x PCIe 3.0 x8 (dual-socket auxiliary connection)
Port Count
2-port
Port Speed & Connector Type
100Gb/s QSFP28 — EDR InfiniBand (100Gb/s) or 100GbE, per port
Network Protocol
VPI — InfiniBand and Ethernet (selectable)
RDMA
Native InfiniBand transport; RoCE v2 (Ethernet mode)
Product Description
The NVIDIA Mellanox ConnectX-5 MCX556M-ECAT-S35A is a dual-port VPI adapter built on NVIDIA's Socket Direct architecture, splitting its PCIe interface into two physical x8 edges (2x PCIe 3.0 x8) via an auxiliary riser/harness instead of a single x16 connector. This gives each CPU socket in a dual-socket server a direct, low-latency PCIe path to the adapter, avoiding cross-socket QPI/UPI hops for data-intensive transfers — an advantage for GPUDirect RDMA, NVMe-oF, and NUMA-sensitive HPC and AI workloads. Built on the MT28808A0-FCCF-EVM controller, it supports 100Gb/s EDR InfiniBand or 100GbE independently on each of its two QSFP28 ports, with native InfiniBand transport offload and RoCE v2 in Ethernet mode. The S35A designation identifies this SKU's specific auxiliary card/riser configuration, distinct from the related S25 SKU; it targets the same class of multi-socket HPC/AI server deployments where balanced, socket-local PCIe bandwidth is required.