NVIDIA Mellanox® MCX4621A-XCAB — ConnectX-4 Lx OCP 3.0 10GbE Dual-Port SFP28 Network Adapter
Technical Identity
The NVIDIA Mellanox® MCX4621A-XCAB is a dual-port 10GbE OCP 3.0 mezzanine network adapter built on the ConnectX-4 Lx EN ASIC. Two SFP28 cages run at 10GbE per port over PCIe 3.0 x8, with host management and a Thumbscrew (Pull-Tab) bracket. Ethernet only (Lx ASIC). Condition: Refurbished Grade A.
Specifications

Brand: NVIDIA Mellanox
Model / MPN: MCX4621A-XCAB
Product family: ConnectX-4 Lx EN
Product type: OCP 3.0 mezzanine Ethernet NIC
Ports: 2 × SFP28 (10GbE per port)
Host interface: PCIe 3.0 x8
Form factor: OCP 3.0 SFF (mezzanine)
Bracket: Thumbscrew (Pull-Tab)
Management: With host / BMC management (NC-SI, MCTP over SMBus / PCIe)
Protocol: Ethernet only (Lx ASIC, no InfiniBand)
Offloads: RoCE v1/v2, NVMe-oF, SR-IOV, ASAP² (hardware-accelerated Open vSwitch), Overlay (VXLAN/NVGRE/Geneve) stateless offloads
Condition: Refurbished Grade A

What This Is NOT

NOT a PCIe add-in card. OCP 3.0 SFF mezzanine — requires an OCP 3.0 SFF/LFF cage on the host. It will NOT slot into a standard PCIe riser.
NOT OCP 2.0 compatible. OCP 3.0 uses a different mechanical connector and cage geometry — OCP 2.0 servers cannot accept this card.
NOT an InfiniBand or VPI adapter. ConnectX-4 Lx is Ethernet only (Lx ASIC). It cannot be switched to InfiniBand via mlxconfig — for VPI / IB, use ConnectX-6 VPI.
NOT a 25GbE variant. SFP28 cage but rated 10GbE on this part number. For 25GbE OCP 3.0 dual-port, see MCX631432AS-ADAB (ConnectX-6 Lx).
NOT a QSFP-family adapter. SFP28 cages only — QSFP28 / QSFP56 / OSFP modules do not fit.
NOT bundled with SFP28 transceivers, DAC/AOC cables, or installation accessories — sold standalone.

Compatibility & Constraints

Host: Server with an OCP 3.0 SFF (or LFF) mezzanine cage and a PCIe 3.0 x8 lane allocation to that slot. Common platforms: Dell PowerEdge 14G/15G with OCP 3.0 riser, HPE ProLiant Gen10+/Gen11 with OCP 3.0 cage, Supermicro X11/X12 OCP 3.0-equipped boards, Lenovo ThinkSystem SR-series, Inspur, Quanta and Wiwynn ODM platforms.
Switch / fabric: Any 10GbE Ethernet switch with SFP+/SFP28 ports — NVIDIA Spectrum SN2010 / SN2100 / SN2700, Cisco Nexus 9300, Arista 7050X / 7280R. SFP28 cages are backward-compatible with SFP+ modules.
Cabling: 10GbE SFP+ DAC, 10GbE SFP+ AOC, or 10GBASE-SR / 10GBASE-LR transceivers. SFP28 25G DAC/AOC will negotiate down to 10G.
Software: MLNX_OFED (Linux) or WinOF-2 (Windows). In-box drivers in current RHEL / SLES / Ubuntu kernels. NC-SI / MCTP for BMC integration (iDRAC, iLO, IPMI).

Frequently Asked Questions (FAQ)
Q. What is the NVIDIA Mellanox MCX4621A-XCAB?
The MCX4621A-XCAB is a dual-port 10GbE OCP 3.0 mezzanine network adapter built on the ConnectX-4 Lx EN ASIC, with two SFP28 cages, PCIe 3.0 x8 host interface, host management, and Thumbscrew (Pull-Tab) bracket. Protocol: Ethernet only (Lx ASIC, no InfiniBand). Condition: Refurbished Grade A.
Q. What connector does the MCX4621A-XCAB use?
SFP28 (x2). The SFP28 cages accept SFP28 25G modules but are rated 10GbE per port on this MPN. SFP+ 10G DAC, AOC and optical transceivers are backward-compatible. QSFP / OSFP modules will NOT fit.
Q. Can the MCX4621A-XCAB fit a standard PCIe slot or an OCP 2.0 slot?
No to both. The MCX4621A-XCAB is OCP 3.0 SFF mezzanine. It will NOT fit a standard PCIe riser, and OCP 3.0 is mechanically incompatible with OCP 2.0 cages. The host server must have an OCP 3.0 SFF/LFF slot wired to PCIe 3.0 x8.
Q. What switches and cables work with the MCX4621A-XCAB?
Any 10GbE Ethernet switch with SFP+/SFP28 ports — NVIDIA Spectrum SN2010 / SN2100, Cisco Nexus 9300, Arista 7050X. Cabling: 10GbE SFP+ DAC, SFP+ AOC, or 10GBASE-SR / 10GBASE-LR transceivers. SFP28 25G DAC/AOC negotiates down to 10G.
Q. Does the MCX4621A-XCAB support RDMA or InfiniBand?
It supports RoCE v1 and v2 (RDMA over Converged Ethernet). It does NOT support native InfiniBand — ConnectX-4 Lx is Ethernet only (Lx ASIC). For VPI / InfiniBand, see ConnectX-6 VPI (MCX653-series).
Q. What workloads does the MCX4621A-XCAB target?
10GbE NVMe-oF storage initiators / targets, virtualized data centers with SR-IOV, software-defined networking (SDN / NFV) with hardware-accelerated Open vSwitch (ASAP²), and 10GbE management or storage uplinks in OCP 3.0 server chassis.
Q. What condition does T.E.S IT-SOLUTIONS supply?
Refurbished Grade A — MPN-identified, EEPROM / vendor-data verified, cosmetically inspected, EU warehouse stock. Anti-static packaging, multi-currency B2B invoicing, worldwide express shipping, and free pre-sale compatibility consultation included.
Why buy from T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS is a Europe-based NVIDIA Mellanox specialist serving HPC, enterprise and data-center procurement teams. Every unit is MPN-identified, NVIDIA P/N matched, EEPROM-verified and cosmetically inspected before leaving our EU warehouse. Multi-currency B2B invoicing, worldwide express shipping, and direct engineering contact for switch / adapter / cable pairing — no call-center, no guessing.