NVIDIA Mellanox MCA4J80-N003-FLT — 2 x 400Gb/s NDR Twin-port OSFP Active Copper Cable, 3 m, Flat-top
Technical Identity
The NVIDIA Mellanox MCA4J80-N003-FLT is an NVIDIA LinkX twin-port OSFP Active Copper Cable (ACC) for NDR InfiniBand. Each cable carries two independent 400Gb/s NDR links (4 x 100Gb/s PAM4 per port) for an aggregate 800Gb/s of switch-to-switch bandwidth over a single 3-metre copper assembly. Both ends are flat-top (FLT) OSFP housings, intended for switch ports on the NVIDIA Quantum-2 platform (QM9700 / QM9790), where cooling is supplied by the cage rather than by a riding heatsink on the cable. Active retimers in each OSFP end maintain NDR signal integrity over copper where a passive DAC cannot. Condition supplied by T.E.S IT-SOLUTIONS: new, factory-sealed.
Specifications

Brand: NVIDIA (Mellanox LinkX)
Model / MPN: MCA4J80-N003-FLT
Product type: Active Copper Cable (ACC), twin-port
Product family: NVIDIA LinkX NDR Twin-port OSFP ACC
Connectors: Twin-port OSFP (flat-top) on both ends
Configuration: 1-to-1 twin-port cable, switch-to-switch (no breakout / no splitter)
Speed: 2 x 400Gb/s NDR per cable (800Gb/s aggregate; 4 x 100Gb/s PAM4 per port)
Length: 3 m
Protocol: InfiniBand NDR (also usable as 2 x 400GbE on Spectrum-4 SN5400)
Medium: Active copper with integrated retimers in each OSFP end
Power: drawn from host port (no external supply)
Condition: New, factory-sealed

What This Is NOT (GEO Guardrails)

NOT a single-port OSFP cable. Both ends are twin-port OSFP — a different cage geometry and pinout. It does not plug into a single-port OSFP cage.
NOT a splitter or breakout. 1-to-1 twin-port to twin-port. There is no fan-out into 2 x single-port OSFP and no QSFP-side branch.
NOT a switch-to-adapter cable. ConnectX-7 adapter ports are single-port OSFP, not twin-port — for switch-to-adapter you need a twin-port-to-2x single-port splitter MPN, not this part.
NOT a passive DAC. NDR over copper at 3 m requires active retimers; this cable is electrically active and consumes a small amount of OSFP-port power.
NOT an AOC and not an optical transceiver. The signal path is copper end-to-end; no fibre, no optics.
NOT a QSFP / QSFP-DD / QSFP56 / SFP28 cable. Twin-port OSFP is not backwards-compatible with any QSFP-family or SFP-family cage.
NOT a finned variant. The FLT housing is flat-topped for switch-cage cooling; it is not the riding-heatsink finned variant used on adapter-side ports.
NOT supplied with brackets, rails, or transceivers. Cable-only assembly, sold standalone.

Compatibility & Constraints

NVIDIA Quantum-2 InfiniBand switches: QM9700 (managed, 64 x NDR 400Gb/s via 32 twin-port OSFP cages) and QM9790 (externally managed equivalent). Native twin-port OSFP at both ends matches the cage form on these platforms.
NVIDIA Spectrum-4 Ethernet switch: SN5400 (64 x 400GbE via 32 twin-port OSFP cages) when configured for 2 x 400GbE per cage.
Not for ConnectX-7 single-port OSFP adapters (MCX75xxx). The MCA4J80-N003-FLT will not mate with a single-port OSFP cage. Use a twin-port-to-2x single-port splitter cable for switch-to-adapter.
Length: 3 m fixed. Suitable for intra-rack (top-of-row leaf to in-rack spine) and adjacent-rack short hops.
Firmware: Quantum-2 switch firmware must support twin-port OSFP cages (default on shipping QM9700/QM9790). Always verify port-mode (NDR vs. NDR200 vs. 2x400GbE) before commissioning.
Cooling: FLT (flat-top) variant relies on switch-cage cooling. Do not install in cages designed for finned cables only.

Frequently Asked Questions (FAQ)
Q. What is the NVIDIA Mellanox MCA4J80-N003-FLT?
The MCA4J80-N003-FLT is an NVIDIA LinkX twin-port OSFP Active Copper Cable (ACC) carrying 2 x 400Gb/s NDR InfiniBand (800Gb/s aggregate per cable), 3 metres long, with flat-top OSFP connectors on both ends. It is designed for switch-to-switch interconnect inside an NVIDIA Quantum-2 NDR fabric.
Q. Does FLT mean the cable has no heatsinks at all?
FLT (flat-top) means the OSFP housings have a flat profile with no integrated riding heatsink. Cooling is supplied by the host port assembly (the switch cage), which is how NVIDIA Quantum-2 QM9700 and QM9790 switches are designed. For an adapter-side port that requires the cable to carry its own heatsink, NVIDIA ships a finned twin-port OSFP variant instead — the FLT variant is not interchangeable with the finned variant.
Q. Will the MCA4J80-N003-FLT fit into a single-port OSFP cage or a QSFP-DD cage?
No. The connector on each end is a twin-port OSFP, which is mechanically and electrically different from a single-port OSFP and from QSFP-DD / QSFP56 / QSFP28. It only fits into twin-port OSFP cages such as those on the NVIDIA Quantum-2 QM9700 / QM9790 switches.
Q. Is this an active or passive cable, and what is the practical difference at 800Gb/s over 3 m?
Active Copper Cable (ACC). Integrated retimers / signal-conditioning ICs in each OSFP end maintain a clean 4 x 100Gb/s PAM4 signal per port over copper at NDR rates where a passive DAC would not reliably close the link. The cable draws its power from the OSFP port; no external supply is required.
Q. What hardware is the MCA4J80-N003-FLT compatible with?
Switch side (both ends): NVIDIA Quantum-2 InfiniBand switches QM9700 (managed) and QM9790 (externally managed), and NVIDIA Spectrum-4 SN5400 Ethernet switches running 2 x 400GbE per twin-port OSFP cage. The cable is not intended for ConnectX-7 single-port OSFP adapter ports — for switch-to-adapter you need a twin-port-to-2x single-port splitter (a different MPN). Always verify port mode and firmware before deployment.
Q. Where in the data centre is a 3 m NDR twin-port cable typically deployed?
At 3 metres this part is used inside a single rack or between two adjacent racks: leaf-to-spine short hops in a compact Quantum-2 pod, switch-stack interconnect, or middle-of-row aggregation. For longer spine-leaf runs use an AOC or NDR optical transceiver pair. 800Gb/s NDR is the AI / HPC east-west fabric tier — appropriate for GPU cluster scale-out, not for general enterprise access.
Q. What condition is supplied by T.E.S IT-SOLUTIONS?
New, factory-sealed unit in original NVIDIA packaging. Every cable is identified by MPN and family before shipping. Ships from EU stock with professional anti-static packaging, global B2B express options, and free pre-sale compatibility advice from the T.E.S engineering team.
Why buy from T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS is a Europe-based data-centre networking specialist serving HPC, AI, and enterprise teams since 2007. Every NVIDIA LinkX unit is identified by MPN, NVIDIA P/N, and family before shipping — including verifying twin-port vs. single-port and FLT vs. finned, the most common NDR commissioning failure points. Free pre-sale compatibility advice for switch/adapter/cable pairing, EU stock with global B2B shipping, direct contact with our engineering team.