NVIDIA Mellanox MCP1660-W02A 400GbE QSFP-DD Passive Copper DAC, 2.5m, 26AWG, LSZH: This is a 2.5-meter passive copper Direct Attach Cable (DAC) terminated with QSFP-DD connectors on both ends, engineered for 400GbE Ethernet (8× 50G PAM4) point-to-point links. NVIDIA P/N: 980-9I35T-00W02A. This IS a passive copper assembly — no active electronics, no power draw, no cooling. This is NOT an active optical cable, NOT a transceiver-plus-patch-cord pair, and NOT a breakout. This is a refurbished unit, tested by T.E.S IT-SOLUTIONS.
Engineering Context
At 2.5 meters and 26 AWG, this DAC sits at the upper end of passive copper reach for 400G PAM4. It runs 8 lanes at 50 Gb/s each (PAM4 signaling) over 8 differential pairs, with an LSZH (Low Smoke Zero Halogen) jacket for fire-code-sensitive data center cabling. Because it is passive, the cable consumes 0 watts and adds essentially zero latency beyond cable propagation — typical for short-reach top-of-rack and adjacent-rack 400G interconnects where optics are over-spec'd and over-priced.
Deployment & Use Cases
Switch-to-switch interconnect inside a rack or between adjacent racks at 400GbE. Server-to-ToR uplinks where the host adapter is QSFP-DD 400G. AI/ML training pods using QSFP-DD-based fabrics. Spine-leaf intra-rack 400GbE without burning optics power budget.
Technical Specifications
OEM: NVIDIA Mellanox
Part Number (MPN): MCP1660-W02A
NVIDIA P/N: 980-9I35T-00W02A
Cable Type: Passive Copper DAC (Direct Attach Copper)
Connectors: QSFP-DD to QSFP-DD (point-to-point)
Data Rate: 400GbE Ethernet (8× 50 Gb/s PAM4)
Length: 2.5 m
Wire Gauge: 26 AWG
Jacket: LSZH (Low Smoke Zero Halogen)
Power Consumption: 0 W (passive)
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Constraints
Compatible with NVIDIA Spectrum-3 / Spectrum-4 switches with QSFP-DD 400G ports and ConnectX-7 QSFP-DD 400G adapters. Requires both endpoints to be QSFP-DD; this is not a QSFP56 (200G) or OSFP cable. This is a straight 1:1 cable — it does NOT break out to 2× 200G or 4× 100G. At 2.5m with 26AWG, this assembly is near the practical limit for 400G passive copper; if your rack-to-rack run exceeds 3m, consider an AOC instead. Switch FEC settings (RS-FEC) must be enabled for 400G PAM4 operation.
Frequently Asked Questions (FAQ)
Q. What is the MCP1660-W02A?
The MCP1660-W02A is a 2.5m passive copper DAC with QSFP-DD connectors, rated for 400GbE Ethernet, 26AWG.
Q. Is this a splitter cable?
No. It is a straight 1-to-1 QSFP-DD-to-QSFP-DD point-to-point assembly.
Q. Will T.E.S IT-SOLUTIONS confirm the configuration of MCP1660-W02A before shipping?
Yes. T.E.S IT-SOLUTIONS (tes-itsolutions.com) bench-tests each unit where test topology is available, before dispatch from EU stock.

Why T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS verifies connector latch integrity, EEPROM identity, and end-to-end signal continuity on every DAC before shipment. Handling time is 1–3 business days, with global shipping and engineer-led cabling guidance.