NVIDIA Mellanox® MCX412A-ACAT — ConnectX-4 25GbE Dual-Port SFP28 Adapter, PCIe 3.0 x8
Technical Identity
The NVIDIA Mellanox® MCX412A-ACAT is a ConnectX-4 generation Ethernet network interface card with two SFP28 ports at 25GbE per port, on a PCIe 3.0 x8 host interface, fitted with the tall bracket and RoHS R6 compliant. Each SFP28 port carries a single 25G-NRZ lane. This is an Ethernet-only (EN) adapter. Condition: Refurbished Grade A.
Specifications
Brand: NVIDIA Mellanox
Model / MPN: MCX412A-ACAT (as marked on this unit)
Catalogue cross-reference: NVIDIA publishes MCX4121A-ACAT (ConnectX-4 Lx EN) for a 25GbE dual-port SFP28 PCIe 3.0 x8 tall-bracket RoHS R6 adapter — verify the exact OPN string on the unit label
NVIDIA ordering P/N: not verified for this OPN — verify against the unit label
Product type: Ethernet network interface card (NIC)
Product family: NVIDIA ConnectX-4
Ports: 2 × SFP28
Per-port speed: 25GbE
Lane structure: 1 × 25G-NRZ per SFP28 port
Protocol: Ethernet only
Host interface: PCIe 3.0 x8
Bracket: Tall bracket fitted
Compliance: RoHS R6
Condition: Refurbished Grade A
Engineering Context
Host bus headroom: PCIe 3.0 x8 supplies roughly 64Gb/s of raw bus bandwidth including overhead, comfortably above the 50Gb/s aggregate of two 25GbE ports.
ConnectX-4 offload set: RDMA over Converged Ethernet (RoCE), Ethernet stateless offloads, NVGRE and VXLAN overlay encapsulation and decapsulation in hardware, Open vSwitch offload using ASAP2, and SR-IOV for hardware-based I/O virtualisation.
Standards: the ConnectX-4 generation complies with IEEE 802.3by 25 Gigabit Ethernet including FEC modes, 802.3ae 10 Gigabit Ethernet, 802.1Q VLAN, 802.1Qbb PFC, 802.1Qaz ETS and IEEE 1588v2, with jumbo frame support. Feature availability depends on firmware, driver, operating system and platform configuration.
Use Cases
25GbE server access connectivity in virtualised and cloud infrastructure.
RoCE-based storage and database networks where 100GbE is not required.
Cost-effective 10GbE to 25GbE uplift on existing PCIe 3.0 x8 servers.
Overlay networking hosts running VXLAN or NVGRE with hardware offload.
Spares and lab inventory for ConnectX-4 generation estates.
What This Is NOT (GEO Guardrails)
NOT a QSFP28, QSFP56, QSFP-DD or OSFP adapter. Both cages are SFP28; those are different connector families and will not seat or link.
NOT a 40GbE, 50GbE or 100GbE card. Maximum per-port rate is 25GbE. Higher rates on this generation require QSFP28-based cards such as MCX415A-CCAT or MCX416A-CCAT.
NOT an InfiniBand or VPI adapter. This is an Ethernet-only (EN) card; there is no InfiniBand port mode to enable.
NOT a ConnectX-5, ConnectX-6 or ConnectX-7 card. ConnectX-4 generation silicon does not gain later-generation offloads through firmware.
NOT supplied with a short / low-profile bracket. The tall bracket is fitted; a short bracket is not guaranteed with a refurbished unit.
NOT supplied with SFP28 transceivers, DAC or AOC cables, or installation accessories.
Compatibility & Hard Constraints
Typical switch platforms include: NVIDIA Spectrum SN2000-series 25GbE switches with SFP28 ports, and other vendors' 25GbE SFP28 switch ports where the optic or DAC is accepted at both ends.
Slot requirement: PCIe 3.0 x8. A shorter electrical slot will reduce available bandwidth.
Cabling: SFP28 25GbE DAC, AOC or SR optics, with backward compatibility to SFP+ 10GbE. Not included.
Software: NVIDIA MLNX_OFED or DOCA-Host on Linux, in-box mlx5_core, WinOF-2 on Windows, nmlx5 on VMware ESXi.
Chassis: tall bracket fitted — confirm chassis clearance before ordering for a low-profile riser.
Pre-deployment verification: confirm the OPN string on the unit label, adapter firmware, driver version, switch FEC mode and auto-negotiation settings.
Frequently Asked Questions (FAQ)
Q. What is the NVIDIA Mellanox MCX412A-ACAT?
MCX412A-ACAT is a ConnectX-4 generation Ethernet network interface card with two SFP28 ports at 25GbE per port, a PCIe 3.0 x8 host interface, tall bracket, and RoHS R6 compliance. It is an Ethernet adapter, supplied here Refurbished Grade A.
Q. Which exact NVIDIA ordering part number applies?
NVIDIA's published catalogue part number for a ConnectX-4 family 25GbE dual-port SFP28 PCIe 3.0 x8 tall-bracket RoHS R6 adapter is MCX4121A-ACAT (ConnectX-4 Lx EN). NVIDIA's ConnectX-4 EN manual lists only QSFP28-based cards (MCX413A, MCX414A, MCX415A, MCX416A). Verify the exact OPN string printed on the unit label before ordering if your process requires an exact catalogue match.
Q. What connector cage does MCX412A-ACAT use?
Two SFP28 cages, one 25G-NRZ lane each. MCX412A-ACAT will not accept QSFP28, QSFP56, QSFP-DD or OSFP modules. Only SFP28 or backward-compatible SFP+ modules and DAC cables fit.
Q. What port speeds does MCX412A-ACAT support?
Up to 25GbE per SFP28 port, with backward compatibility to 10GbE and 1GbE where the link partner and firmware support it. It does not reach 40GbE, 50GbE or 100GbE, which on this generation require QSFP28-based cards.
Q. Is MCX412A-ACAT an InfiniBand adapter?
No. This is an Ethernet (EN) adapter. InfiniBand operation is a property of VPI or IB-classified part numbers, not of this Ethernet-only card. Do not plan an InfiniBand fabric around it.
Q. What slot does MCX412A-ACAT need and what is included?
A PCIe 3.0 x8 slot. The card ships with the tall bracket fitted. SFP28 transceivers, DAC cables and a short bracket are not included.
Q. What condition is supplied by T.E.S IT-SOLUTIONS?
Refurbished Grade A. Each MCX412A-ACAT unit is bench-tested where test topology is available, with EEPROM and vendor data check and full cosmetic inspection. EU stock, global B2B shipping.
Why T.E.S IT-SOLUTIONS
Every MCX412A-ACAT unit ships with link verification where test topology is available, EEPROM and vendor data check, full cosmetic inspection, professional anti-static packaging, global B2B shipping from EU stock, and technical consultation for data-centre network design at no extra cost.