NVIDIA Mellanox MCX556M-EDAT ConnectX-5 Ex VPI Socket Direct Adapter, EDR IB / 100GbE, Dual-Port QSFP28: This is a Virtual Protocol Interconnect (VPI) adapter card based on the ConnectX-5 Ex ASIC, supporting both InfiniBand EDR (100Gb/s) and 100GbE Ethernet on the same dual QSFP28 ports. The card uses Socket Direct technology with two PCIe 3.0 x8 connections (auxiliary card included via I-PEX harness), allowing each CPU socket on a dual-socket server to connect directly to one network port. This is a dual-card Socket Direct assembly with tall bracket — not a single PCIe 3.0 x16 card. This is a refurbished unit.
Engineering Context
Socket Direct technology eliminates inter-socket traffic by giving each CPU its own PCIe 3.0 x8 path to one of the two network ports, reducing latency and freeing up QPI/UPI bandwidth on dual-socket Xeon and EPYC servers. The ConnectX-5 Ex controller supports RoCEv2, GPUDirect RDMA, NVMe-oF, SR-IOV, and InfiniBand verbs. As a VPI card, each port can independently run InfiniBand EDR or 100GbE based on the firmware configuration. Latency under RoCE is sub-microsecond.
Deployment & Use Cases
HPC clusters running InfiniBand EDR with MPI workloads (LAMMPS, GROMACS, OpenFOAM). AI/ML training nodes leveraging GPUDirect RDMA to NVIDIA GPUs across InfiniBand. Storage fabrics combining NVMe-oF over RoCEv2 or SRP over InfiniBand. Dual-socket servers (Intel Xeon Scalable, AMD EPYC) where Socket Direct lowers cross-NUMA latency. Mixed-protocol environments where one port runs IB and the other 100GbE.
Technical Specifications
OEM: NVIDIA Mellanox
Part Number: MCX556M-EDAT
Controller: ConnectX-5 Ex
Protocol: VPI (InfiniBand EDR + 100GbE Ethernet)
Ports: Dual-Port QSFP28
Data Rate: 100Gb/s per port (EDR IB or 100GbE)
Host Interface: Socket Direct — 2x PCIe 3.0 x8
Form Factor: Dual-card Socket Direct with I-PEX harness
Bracket: Tall bracket
Key Features: RoCEv2, GPUDirect RDMA, SR-IOV, NVMe-oF
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Hard Constraints
Requires a dual-socket server with two available PCIe 3.0 x8 (or larger) slots — one slot per CPU socket — and adequate routing for the I-PEX auxiliary harness. Not compatible with single-socket servers; Socket Direct is wasted without a second CPU socket. Each port runs at 100Gb/s; the card cannot be used as a single PCIe 4.0 x16 device. Requires NVIDIA Mellanox OFED or upstream MLNX drivers for full feature support. EDR IB requires Mellanox SB7700/SB7800 or compatible IB switches; 100GbE requires Spectrum or compatible Ethernet switches. Tall bracket only — no low-profile option.
Why Choose T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS tests every Socket Direct adapter on a dual-socket reference platform, validating both PCIe x8 connections, port link training in IB and Ethernet modes, and firmware version. We provide expert consultation on HPC and AI fabric design, global shipping, and 1–3 day handling. Visit tes-itsolutions.com for our full catalog.