NVIDIA Mellanox MCX512A-ADAT ConnectX-5 Ex EN Dual-Port 25GbE SFP28 Adapter: This is a ConnectX-5 Ex Ethernet-only host adapter with two SFP28 ports running at 25GbE per port. The card seats in a single PCIe slot — Gen3 x8 or Gen4 x8 host interface — and ships with a tall (full-height) bracket. This is a 25GbE NIC, not a 100GbE adapter and not a VPI (InfiniBand) card. This is a refurbished unit.
Engineering Context
ConnectX-5 Ex silicon adds PCIe Gen4 x8 support over the standard ConnectX-5, giving roughly 128 Gb/s of usable host bandwidth on Gen4 platforms — well above the 50 Gb/s the two 25GbE ports can drive. Each SFP28 port carries 25Gb/s NRZ. The card supports RoCEv2 for kernel-bypass RDMA over converged Ethernet, NVMe-oF target/initiator, T10-DIF integrity offload, ASAP² OVS offload, and stateless TCP/UDP/IP offloads. Embedded PCIe switch and PCIe Advanced Error Reporting are present.
Deployment & Use Cases
25GbE rack uplinks for Top-of-Rack switching. Hyperconverged infrastructure (Nutanix, vSAN, Hyper-V S2D) over RoCEv2. NVMe-oF storage initiators connecting to all-flash arrays. Dual-rail bonding (LACP / Active-Backup) for HA web tiers. Spine-leaf 25GbE Ethernet fabrics built on Spectrum or third-party switches.
Technical Specifications
OEM: NVIDIA Mellanox
Part Number: MCX512A-ADAT
Family: ConnectX-5 Ex EN (Ethernet only)
Ports: Dual SFP28
Data Rate: 25GbE per port (NRZ)
Host Interface: PCIe Gen3 x8 / Gen4 x8
Bracket: Tall (Full-Height)
RDMA: RoCEv2
Offloads: NVMe-oF, T10-DIF, ASAP² OVS, stateless TCP/UDP/IP
Driver: MLNX_OFED / WinOF-2 / inbox kernel drivers
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Constraints
Requires one PCIe x8 slot (Gen3 or Gen4) electrically; mechanically the card is x8 length. Compatible with NVIDIA Spectrum/Spectrum-2 25GbE switches and any standards-based 25GbE Ethernet switch. SFP28 ports are backward compatible with 10GbE SFP+ optics and DACs (auto-negotiated speed). Not an InfiniBand card — it will not link to QM/MSB EDR/HDR switches. Not compatible with QSFP28 cables/transceivers (form factor mismatch). Not designed for 100GbE — that requires MCX516A or MCX556A.
Why Choose T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS power-tests every ConnectX-5 Ex card, validates 25Gb/s link training on both SFP28 ports, and verifies firmware rev. Visit https://www.tes-itsolutions.com/ for our full Mellanox Ethernet adapter catalog. Handling time: 1–3 business days.