NVIDIA Mellanox ConnectX-4 Lx EN MCX4121A-ACAT
Dual-Port 25GbE PCIe 3.0 x8 Adapter Card
Host Interface
PCIe 3.0 x8
Port Count
2-port
Port Speed & Connector Type
25GbE, SFP28, per port
Form Factor
Standard-height PCIe adapter card
Network Protocol / RDMA
Ethernet with RoCE v2 (RDMA over Converged Ethernet)
Product Description
The NVIDIA Mellanox ConnectX-4 Lx EN MCX4121A-ACAT is a dual-port 25 Gigabit Ethernet adapter that pairs the higher-bandwidth 25GbE SFP28 interface with the full ConnectX-4 Lx hardware offload set — QoS, CPU offloads, jumbo frames, storage acceleration, SR-IOV, NC-SI, LLDP and QCN — across two independent ports. Built around the MT27712A0-FDCF-AE controller and connecting via PCIe 3.0 x8, it supports RoCE v2 hardware-accelerated RDMA and SR-IOV-based VM network virtualization, making it well suited for dual-homed, high-throughput server designs in virtualized cloud and storage-intensive environments. This model shares its physical appearance with the 10GbE MCX4121A-XCAT and is also shipped under compatible OEM part numbers by major server vendors — Huawei (06310106), Lenovo (01GR253) and IBM (01LJ590) — reflecting its broad adoption as a standard dual-port 25GbE NIC across the OEM server ecosystem.