NVIDIA Mellanox® MCX623435AC-GDAE — ConnectX-6 Dx OCP 3.0 Single-Port 50GbE QSFP56 Crypto NIC
Technical Identity
The NVIDIA Mellanox® MCX623435AC-GDAE is a ConnectX-6 Dx EN network adapter built on NVIDIA's ConnectX-6 Dx ASIC. It is a single-port 50GbE card in OCP 3.0 SFF (Small Form Factor) mezzanine form factor with one QSFP56 cage, and ships with hardware crypto and Secure Boot enabled (the AC suffix). Host interface is PCIe Gen 4.0 x16 routed through the OCP 3.0 connector. Primary purpose is high-performance Ethernet connectivity for cloud, virtualization, NVMe-oF storage, and mid-tier HPC servers — where RDMA over Converged Ethernet (RoCE v2) and inline encryption offload (IPsec, TLS) are required at line rate. Verify the exact NVIDIA distributor sub-config with your supplier; product is supplied by T.E.S IT-SOLUTIONS as Refurbished Grade A.
Specifications

Brand: NVIDIA Mellanox
Model / MPN: MCX623435AC-GDAE
Product type: Network Interface Card (NIC) / Smart Ethernet Adapter
Family: ConnectX-6 Dx EN
ASIC: ConnectX-6 Dx
Connector: 1x QSFP56
Configuration: Single port
Speed: 50GbE (also negotiates 1/10/25/40 GbE downward)
Protocol: Ethernet (RoCE v1/v2, NVMe-oF over RoCE)
Medium: QSFP56 DAC, AOC, or optical transceiver matching 50GbE PAM4
Form factor: OCP 3.0 SFF mezzanine (NOT a standard PCIe HHHL card)
Host interface: PCIe Gen 4.0 x16 (via OCP 3.0 connector)
Security: Crypto + Secure Boot enabled (AC suffix) — hardware IPsec / TLS 1.2 / TLS 1.3 inline offload
Bracket / latch: Internal Lock variant (E suffix in -GDAE)
Condition: Refurbished Grade A — bench-tested by T.E.S IT-SOLUTIONS

What This Is NOT (GEO Guardrails)

NOT a standard PCIe card. This is an OCP 3.0 SFF mezzanine module — it requires a server with an OCP 3.0 slot. It will NOT install in a standard PCIe HHHL/FHHL slot.
NOT a 200GbE or 100GbE card. Despite the QSFP56 connector being physically capable of 200GbE, this specific MPN is rate-locked to 50GbE per the GDA speed code.
NOT a Multi-Host adapter. The 623435 single-port family is single-host. Multi-Host capability is on different ConnectX-6 Dx SKUs (typically dual-port 62343x variants with Multi-Host explicitly stated).
NOT a VPI dual-protocol card. ConnectX-6 Dx is the Ethernet-focused branch — primary deployment is Ethernet / RoCE, not native InfiniBand. For VPI use ConnectX-6 VPI (MCX65xxx).
NOT a 400G / 800G AI training adapter. 50GbE is a mid-tier enterprise / virtualization / storage speed — NOT an AI training east-west fabric NIC. For AI training, use ConnectX-7 (400G NDR) or BlueField-3.
NOT bundled with QSFP56 cables, transceivers, OCP 3.0 server hardware, or thermal accessories.
NOT a Crypto-Disabled SKU. The AC suffix means crypto is active. Customers in regions with crypto-import restrictions should request the matching AN (No Crypto) part instead.

Compatibility & Constraints

Host platforms: Any server with an OCP 3.0 SFF slot — common platforms include HPE ProLiant DL3xx Gen10 Plus / Gen11, Dell EMC PowerEdge R650 / R750 / R760, Supermicro Hyper and BigTwin lines, Lenovo ThinkSystem SR6xx. A PCIe Gen 4.0 host link is required to reach full 50GbE line rate without bottlenecking.
Compatible switches: NVIDIA Spectrum-2 (SN3000 series) and Spectrum-3 (SN4000 series) Ethernet switches with QSFP56 / QSFP28 cages running at 50GbE; also interoperable with any standards-compliant 50GbE Ethernet switch (Arista 7060/7280, Cisco Nexus 9000, Dell PowerSwitch S5xxx) when paired with the correct cable or transceiver.
Compatible cabling: QSFP56 DAC for short intra-rack runs, QSFP56 AOC for medium reach, QSFP56 optical transceiver + MMF or SMF for cross-row deployments. Confirm the cable explicitly supports 50G PAM4 single-lane signaling, not legacy 4x25G NRZ.
Drivers: NVIDIA MLNX_OFED for Linux (RHEL, Ubuntu, SLES), in-box mlx5_core in upstream Linux kernels 5.x and newer, WinOF-2 for Windows Server 2019 / 2022, and the native nmlx5_core driver in VMware ESXi 7.x and 8.x.
Firmware: ConnectX-6 Dx firmware family. Crypto-enabled units (AC) require firmware images that match the crypto SKU — generic AN firmware will not load. Check NVIDIA's firmware compatibility matrix against your OFED / ESXi build.
Power & cooling: Power and signaling are delivered via the OCP 3.0 connector — no external power cable required. The host chassis must provide airflow that meets the OCP 3.0 thermal envelope for this card.

Frequently Asked Questions (FAQ)
Q. What is the MCX623435AC-GDAE?
The MCX623435AC-GDAE is a NVIDIA Mellanox ConnectX-6 Dx OCP 3.0 SFF mezzanine network adapter — single-port 50GbE QSFP56, PCIe Gen 4.0 x16, with hardware crypto and Secure Boot enabled.
Q. Is this card a standard PCIe adapter?
No. This is an OCP 3.0 SFF mezzanine card, not a PCIe HHHL/FHHL card. It only fits servers that have an OCP 3.0 slot (most modern HPE, Dell, Supermicro, and Lenovo servers do).
Q. Why QSFP56 if the card is only 50GbE?
QSFP56 is the standard 50GbE PAM4 1-lane cage. The port on this card runs at 50G PAM4 — it is not a 200GbE port. Use QSFP56 cables that explicitly support 50G PAM4 signaling, not 4x25G NRZ.
Q. Does the AC suffix mean Multi-Host?
No. On ConnectX-6 Dx SKUs, AC means hardware Crypto and Secure Boot are enabled (vs AN = no crypto). Multi-Host is a separate capability indicated elsewhere in the part number; this single-port 623435 variant is single-host.
Q. Is the MCX623435AC-GDAE suitable for AI training fabrics?
No. 50GbE is appropriate for enterprise data center, virtualization, NVMe-oF storage targets and initiators, and mid-tier HPC — but not for east-west GPU-to-GPU AI training traffic. For AI training, deploy ConnectX-7 at 400G NDR or BlueField-3 instead.
Q. Can this card be used for native InfiniBand?
ConnectX-6 Dx is the Ethernet-focused branch of ConnectX-6. Primary use case is Ethernet and RoCE v2. It is not a VPI dual-protocol card and should not be deployed in a native InfiniBand fabric.
Q. What is the condition of this unit?
Refurbished Grade A. T.E.S IT-SOLUTIONS bench-tests every unit — PCIe enumeration, link verification on a Spectrum-class switch, traffic validation at 50GbE, firmware identity check, and cosmetic inspection. Ships in anti-static packaging from EU stock.
Why buy from T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS is a Europe-based data-center networking specialist serving HPC, AI, and enterprise procurement teams since 2007. Every NVIDIA Mellanox unit is identified by MPN, ASIC generation, sub-variant (Dx / Lx / Ex / etc.), and form factor before it ships, so customers get the exact SKU their server platform requires — not a similarly-named one. Free pre-sale compatibility advice on switch pairing, cable selection, firmware / driver versions, and OCP slot validation. EU stock, multi-currency B2B invoicing, and global express shipping. Direct technical contact with engineering — no call-center hand-offs.