NVIDIA Mellanox MCX313A-BCBT ConnectX-3 EN Single-Port 40/56GbE QSFP+ Network Adapter, PCIe 3.0 x8: This is a single-port QSFP+ Ethernet network interface card (NIC) based on the Mellanox ConnectX-3 EN ASIC. It delivers 40GbE standard or 56GbE (Mellanox FDR-encoded) per port over a PCIe 3.0 x8 host interface. This is an Ethernet-only adapter (EN suffix), not the VPI dual-mode variant; it does not run InfiniBand. This unit is refurbished, lab-tested by T.E.S IT-SOLUTIONS.
Engineering Context
The ConnectX-3 EN ASIC implements stateless TCP/UDP/IP offloads, RDMA over Converged Ethernet v1/v2 (RoCE), SR-IOV with up to 127 virtual functions, and hardware VLAN tagging. The 40GbE link uses 4x10G NRZ lanes at 64b/66b encoding; 56GbE adds Mellanox proprietary FDR-encoded signaling for ~14% higher throughput between Mellanox endpoints. The host PCIe 3.0 x8 interface delivers ~64Gb/s effective bandwidth, sufficient to saturate a 56GbE port. The card supports MSI-X interrupt steering and TSS/RSS queue distribution for multi-core scaling. Mellanox MFT and MLNX_OFED Linux/Windows drivers provide management, firmware, and tuning tools.
Deployment & Use Cases
40GbE server connectivity to Mellanox SwitchX-2 (SX1036, SX1024) and NVIDIA Spectrum SN2410 switches. RoCE-accelerated storage fabrics (Ceph, Lustre, NFSoRDMA) where low CPU overhead is required. Hyperconverged infrastructure (HCI) nodes (VMware vSAN, Microsoft S2D) with high east-west bandwidth needs. Server-virtualization hosts using SR-IOV passthrough for low-latency tenant networking.
Technical Specifications
OEM: NVIDIA Mellanox
Part Number: MCX313A-BCBT
ASIC: Mellanox ConnectX-3 EN
Ports: 1 x QSFP+
Link Speed: 40GbE / 56GbE (Mellanox FDR-encoded)
Host Interface: PCIe 3.0 x8 (8GT/s)
Form Factor: Standard PCIe
Network Stack Offloads: TCP/UDP/IP stateless, RoCE v1/v2
Virtualization: SR-IOV up to 127 VFs
Interrupts & Steering: MSI-X, TSS/RSS multi-queue
Driver Support: MLNX_OFED for Linux, WinOF for Windows
Connector: QSFP+ (40/56GbE, optical or copper)
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Hard Constraints
Compatible with Mellanox SwitchX-2, NVIDIA Spectrum, and standards-compliant 40GbE switches from Cisco, Arista, Juniper, and Dell. The 56GbE link rate is supported only between Mellanox endpoints (NIC-to-NIC or NIC-to-SwitchX-2); third-party switches will negotiate down to 40GbE. This is an Ethernet-only adapter; it does NOT support InfiniBand operation (no VPI). The QSFP+ cage uses 4x10G NRZ lanes; it does NOT support 100GbE QSFP28 cables (those require ConnectX-4/5/6 or later). Linux kernel 3.10+ or Windows Server 2012 R2+ recommended for full feature support. Older firmware may be required for compatibility with legacy switch firmware; consult the NVIDIA/Mellanox firmware compatibility matrix.
Why Choose T.E.S IT-SOLUTIONS
Every ConnectX-3 NIC is bench-tested for PCIe enumeration, link-up at 40GbE, and EEPROM/firmware integrity before shipment. Visit tes-itsolutions.com for global shipping and 1–3 day handling.
Frequently Asked Questions
What host interface does the MCX313A-BCBT have?
The MCX313A-BCBT host interface is PCIe 3.0 x8 (8GT/s), as listed in the specifications for MCX313A-BCBT.
What is the MCX313A-BCBT NOT compatible with?
it does not run InfiniBand. Confirm fitment against your platform before ordering MCX313A-BCBT.
What condition is the MCX313A-BCBT supplied in, and who sells it?
The MCX313A-BCBT is supplied in Refurbished condition by T.E.S IT-SOLUTIONS from EU stock, with 1-3 business day handling and worldwide B2B shipping. See https://www.tes-itsolutions.com/product-page/mellanox-mcx313a-bcbt-referbushed.