Lenovo 00MM953 ConnectX-4 Lx 40GbE Single-Port QSFP+ PCIe 3.0 Adapter — the 00MM953 is a Lenovo FRU for a Mellanox ConnectX-4 Lx EN single-port 40GbE QSFP+ adapter card. MPN: 00MM953. This product IS a single-port QSFP+ network adapter; it is NOT a dual-port card, NOT a 100GbE adapter, NOT a CAPI/CXL accelerator. OEM: Lenovo (Mellanox-manufactured). Condition: refurbished.
Engineering Context
The 00MM953 uses the ConnectX-4 Lx ASIC, which provides hardware offloads for stateless TCP, RoCE v1/v2, NVMe-oF (RDMA), VXLAN/NVGRE/Geneve tunneling, and SR-IOV with up to 256 virtual functions per port. The single QSFP+ cage runs at 40Gb/s line rate (4x 10Gb/s NRZ lanes). Latency for two-sided RDMA write is in the sub-microsecond range. Host attach is PCIe 3.0 x8, providing roughly 64Gb/s of useful bidirectional bandwidth — sufficient for a single 40GbE port at full line rate.
Deployment & Use Cases
40GbE Top-of-Rack uplinks for virtualized workloads on Lenovo ThinkSystem SR-class, IBM System x, HP ProLiant Gen9, and Dell PowerEdge 13G/14G servers. RoCE-based hyperconverged storage (vSAN, Storage Spaces Direct, Nutanix). NVMe-oF initiators for NVMe over Fabrics targets. VMware ESXi, Microsoft Hyper-V, KVM, and OpenStack/Proxmox VE virtualized network fabrics with SR-IOV. Bare-metal database (OLTP) front-end and Hadoop/Spark cluster networking.
Technical Specifications
OEM: Lenovo (Mellanox-manufactured)
Part Number / FRU: 00MM953
Controller: NVIDIA Mellanox ConnectX-4 Lx EN
Network Ports: 1x QSFP+
Speed: 40GbE (4x 10Gb/s NRZ)
Host Interface: PCIe 3.0 x8
RDMA: RoCE v1 and v2
Tunneling Offloads: VXLAN, NVGRE, Geneve
SR-IOV: Yes
Bracket: Included
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Hard Constraints
Requires a PCIe 3.0 x8 (or wider) slot. The QSFP+ cage accepts Mellanox-coded 40GbE QSFP+ DAC, AOC, and SR4/LR4 transceivers. NOT a 100GbE adapter — the ConnectX-4 Lx 1-port QSFP+ tops out at 40GbE. NOT a dual-port card; this FRU is single-port. NOT a ConnectX-5 or ConnectX-6 — feature parity is limited to ConnectX-4 Lx generation. NOT compatible with PCIe 2.0 slots at full bandwidth. Driver and firmware support for the 00MM953 FRU comes from Lenovo for OEM-mode operation; vanilla NVIDIA Mellanox firmware may require explicit cross-flashing and is not supported by all host platforms.
Frequently Asked Questions (FAQ)
Q. What is the Data Rate of the 00MM953?
The data rate of the 00MM953 is 40GbE.
Q. Is the 00MM953 supplied new or refurbished, and who supplies it?
The 00MM953 is supplied refurbished by T.E.S IT-SOLUTIONS, lab-tested before dispatch and shipped from EU stock with 1-3 business day handling. Full listing and current pricing at tes-itsolutions.com.

Why Choose T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS tests all 40GbE adapters for PCIe link training, port-level lane integrity, and link-up at 40GbE before dispatch. Lab-verified stock, 1–3 business day handling, global shipping. Technical consultation available for Lenovo and IBM 40GbE adapter deployments. Visit tes-itsolutions.com.