NVIDIA Mellanox MCX556M-ECAT-S35A ConnectX-5 VPI Dual-Port 100GbE/EDR Adapter, Socket Direct (35cm): This is a ConnectX-5 VPI host channel adapter with Socket Direct architecture. The card presents two PCIe Gen3 x8 connectors joined by a 35cm internal harness, allowing each QSFP28 port to bind directly to a separate CPU socket in a dual-socket server. This is a dual-port adapter card, not a single-PCIe NIC and not a switch. NVIDIA P/N 900-9X5AD-0056-DT2. This is a refurbished unit.
Engineering Context
ConnectX-5 silicon carries both EDR InfiniBand (100Gb/s, 4x 25.78125Gb/s NRZ) and 100Gb Ethernet (4x 25Gb/s NRZ) on the same QSFP28 cage. The 35cm Socket Direct harness allows each port to traverse its own PCIe Gen3 x8 link (theoretical ~64 Gb/s usable) into a different CPU socket, bypassing inter-socket UPI/QPI hops for network I/O. Hardware offloads include RoCEv2, NVMe-over-Fabrics target, T10-DIF, erasure-coding offload, and stateless TCP/UDP/IP offload.
Deployment & Use Cases
EDR InfiniBand HPC fabrics running MPI (OpenMPI, MVAPICH2, Intel MPI). NUMA-balanced AI training nodes where each GPU complex is paired with a local 100Gb port. NVMe-oF target and initiator nodes. Lustre, GPFS (Spectrum Scale), BeeGFS, Ceph storage spine. Dual-rail HDR-100/EDR clusters (each rail bound to its own socket).
Technical Specifications
OEM: NVIDIA Mellanox
Part Number: MCX556M-ECAT-S35A (NVIDIA P/N 900-9X5AD-0056-DT2)
Family: ConnectX-5 VPI
Ports: Dual QSFP28
Data Rate: 100Gb/s EDR InfiniBand and 100GbE per port
Host Interface: 2x PCIe Gen3 x8 (Socket Direct)
Auxiliary Harness: 35cm
Bracket: Tall (Full-Height)
Offloads: RoCEv2, NVMe-oF, T10-DIF, erasure coding
Architecture: Socket Direct (dual-PCIe)
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Constraints
Requires a dual-socket server with two free PCIe Gen3 x8 (or wider) slots, one per socket, and physical clearance to route the 35cm aux harness across the chassis. Compatible with NVIDIA Quantum/Switch-IB EDR InfiniBand switches (e.g., MSB7790, QM8700 in EDR mode) and Spectrum/Spectrum-2 100GbE switches. Driver: MLNX_OFED for Linux, WinOF-2 for Windows. Not compatible with single-slot servers, PCIe Gen2-only chassis (will negotiate down), or HDR (200Gb/s) fabrics — HDR requires ConnectX-6.
Why Choose T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS power-tests every ConnectX-5 adapter, validates link training at 100Gb/s on both ports, and inspects the Socket Direct harness for continuity. Visit https://www.tes-itsolutions.com/ for the full Mellanox catalog. Handling time: 1–3 business days.