NVIDIA Mellanox MCX312B-XCDT ConnectX-3 Pro EN Adapter Card, Single-Port SFP+, 10GbE: This is a single-port 10 Gigabit Ethernet network interface card based on NVIDIA Mellanox ConnectX-3 Pro silicon. Single SFP+ cage on a PCIe 3.0 x8 host interface. This is NOT the dual-port MCX312B-XCBT variant, and not the QSFP-based 40GbE MCX313A series. This is an Ethernet-only NIC; it does NOT support InfiniBand. This is a refurbished unit tested by T.E.S IT-SOLUTIONS.
Engineering Context
The card uses one ConnectX-3 Pro ASIC and exposes a single SFP+ cage that supports SFP+ direct-attach copper (DAC) cables, 10GBASE-SR/LR optical transceivers, and 10GBASE-T copper SFP+ modules. The PCIe 3.0 x8 host interface (8GT/s per lane) provides ~63Gb/s of aggregate bandwidth, far in excess of a single 10GbE port — leaving full headroom for SR-IOV virtualization and offloads. Pro silicon adds RoCE v2 and VXLAN/NVGRE encapsulation/decapsulation offloads. SR-IOV supports up to 127 virtual functions. Standard stateless TCP offloads (TSO, LSO, GRO) are supported.
Deployment & Use Cases
10GbE host uplinks for storage servers (Ceph, NFS, iSCSI, iSER). Virtualization hosts (VMware ESXi, KVM, Hyper-V) with SR-IOV passthrough. RDMA-enabled workloads using RoCE v2 over routed Ethernet. Data center top-of-rack server attach. Software-defined networking deployments using VXLAN or NVGRE overlays where Pro offloads matter. Replacement for older Intel X520 / Broadcom 57810 cards needing higher PCIe bandwidth headroom.
Technical Specifications
OEM: NVIDIA Mellanox
Part Number (MPN): MCX312B-XCDT
Product Line: ConnectX-3 Pro EN
Ports: Single-Port SFP+
Ethernet Speed: 10GbE
Protocol Mode: Ethernet only
Host Interface: PCIe 3.0 x8 (8GT/s)
Form Factor: PCIe Low-Profile (with bracket adapter)
RDMA: RoCE v1 and RoCE v2
Overlay Offloads: VXLAN, NVGRE encap/decap
Virtualization: SR-IOV (up to 127 VFs)
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Hard Constraints
Requires a PCIe 3.0 x8 (or wider) slot. PCIe 2.0 slots will work but bandwidth is halved. Compatible with most third-party 10GbE switches at standard SFP+ speeds; SFP+ DAC cables and SR/LR transceivers from Mellanox, Cisco-coded, Arista-coded, and generic vendors are typically interoperable. Driver support requires MLNX_OFED or upstream Linux mlx4 drivers; the ConnectX-3 generation is NOT supported by the newer mlx5 driver. Does NOT support 25GbE — the SFP+ cage is hard-limited to 10G. Does NOT support InfiniBand. Single-port card only — no port aggregation across two cables on this SKU.
Why Choose T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS bench-tests every ConnectX-3 Pro EN card for 10GbE link training, RoCE loopback, and PCIe link width before shipment. Visit T.E.S IT-SOLUTIONS for warranty terms and global shipping. Standard handling time 1–3 business days.
Frequently Asked Questions
What host interface does the MCX312B-XCDT have?
The MCX312B-XCDT host interface is PCIe 3.0 x8 (8GT/s), as listed in the specifications for MCX312B-XCDT.
What is the MCX312B-XCDT NOT compatible with?
This is NOT the dual-port MCX312B-XCBT variant, and not the QSFP-based 40GbE MCX313A series. Confirm fitment against your platform before ordering MCX312B-XCDT.
What condition is the MCX312B-XCDT supplied in, and who sells it?
The MCX312B-XCDT 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-mcx312b-xcdt-10gbe-ethernet-network-card-single-port-spf-pcie3-0-x8.