NVIDIA Mellanox MCX314A-BCBT ConnectX-3 EN Dual-Port 40/56GbE QSFP+ Network Adapter, PCIe 3.0 x8: This is a ConnectX-3 EN (Ethernet-only) Network Interface Card with two QSFP+ ports, each capable of 40GbE standard or 56GbE FDR-Ethernet (Mellanox-to-Mellanox proprietary mode). Host interface is PCIe 3.0 x8 at 8 GT/s, providing approximately 64Gb/s of bus bandwidth. The card ships with a tall (full-height) bracket. This is an EN (Ethernet-only) variant — it is NOT a VPI card and CANNOT be configured for InfiniBand. RoHS R6 certified. This is a refurbished unit.
Engineering Context
ConnectX-3 EN provides RDMA over Converged Ethernet (RoCEv1) and SR-IOV with up to 127 virtual functions, enabling efficient virtualization in KVM, ESXi, and Hyper-V environments. The 56GbE mode is a Mellanox-proprietary speed used between two ConnectX-3 EN ports or to a SwitchX-2 switch — it is not interoperable with non-Mellanox 40GbE infrastructure. PCIe 3.0 x8 at 64Gb/s caps aggregate dual-port throughput; saturating both ports at 40GbE simultaneously is bus-limited. The card supports stateless TCP/UDP/IP offload, VXLAN/NVGRE hardware offload, and traffic classification.
Deployment & Use Cases
40GbE storage server uplinks for NFS, iSCSI, and SMB Direct. Dual-homed virtualization hosts requiring SR-IOV for guest VMs. Mellanox-to-Mellanox 56GbE links between ConnectX-3 EN servers and SwitchX-2 switches in legacy lab or test fabrics. Bridging older 10/40GbE infrastructure with modern Spectrum platforms via standard 40GbE. NOT suitable for new HDR/EDR InfiniBand or 100GbE deployments — use ConnectX-5 or ConnectX-6 for those.
Technical Specifications
OEM: NVIDIA Mellanox
Part Number: MCX314A-BCBT
Architecture: ConnectX-3 EN
Ports: 2× QSFP+
Data Rate (per port): 40GbE standard, 56GbE Mellanox-proprietary
Host Interface: PCIe 3.0 x8 (8 GT/s)
RDMA: RoCEv1
SR-IOV: Up to 127 VFs
Offloads: TCP/UDP/IP, VXLAN, NVGRE
Bracket: Tall (full-height)
Compliance: RoHS R6
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Hard Constraints
Compatible with PCIe 3.0 x8 (or higher) host slots and Mellanox/NVIDIA QSFP+ DACs, AOCs, and 40GBASE-SR4/LR4 transceivers. 56GbE mode requires Mellanox SwitchX-2 (e.g., MSX1024B/MSX1036B) or a peer ConnectX-3 EN port — it is NOT a standard speed and will not interoperate with Spectrum, Tomahawk, or third-party Ethernet switches. This is an Ethernet-only (EN) SKU; for VPI dual-mode (Ethernet/IB) capability use MCX354A-FCBT or similar. Does NOT support 25GbE, 50GbE, or 100GbE — use ConnectX-4 Lx or ConnectX-5 for those speeds.
Why Choose T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS bench-tests every ConnectX-3 EN adapter for PCIe link width, both QSFP+ ports at 40GbE, and firmware boot before shipment. Visit tes-itsolutions.com for our full ConnectX adapter inventory. Handling time 1–3 business days with global express shipping and warranty.