NVIDIA Mellanox MCP1660-W003E26 400GbE QSFP-DD Passive Direct Attach Copper Cable, 3m, 26AWG: This is a 3-meter passive copper twinax DAC for 400Gb/s Ethernet (400GbE) point-to-point interconnect. The cable is QSFP-DD to QSFP-DD with 26AWG conductors and an LSZH jacket. This is a fixed-length factory-terminated assembly, not a transceiver pair. This is a brand-new, factory-sealed unit.
Engineering Context
The MCP1660-W003E26 carries 8 lanes of 50Gb/s PAM4 to deliver 400GbE aggregate per IEEE 802.3cd / 802.3ck-class signaling. Passive copper has no active electronics: zero retimer power and the lowest possible latency, but a tighter reach budget than active copper or AOC. At 3m on 26AWG, link margin is engineered for 400GbE PAM4 with the host-side FEC of modern Spectrum-class switches and ConnectX-7 NICs. The LSZH jacket meets data-center fire-safety codes. Bend radius and bulk are higher than for an AOC of the same length.
Deployment & Use Cases
Top-of-Rack 400GbE switch-to-switch and switch-to-server links inside a single rack. AI training pods linking GPU servers to Spectrum-3 or Spectrum-4 leaf switches. High-density 400GbE aggregation where power and latency budgets favor passive copper over optics.
Technical Specifications
OEM: NVIDIA Mellanox
Part Number: MCP1660-W003E26
Form Factor: QSFP-DD to QSFP-DD (point-to-point)
Cable Type: Passive Direct Attach Copper (DAC)
Data Rate: 400GbE (8 x 50Gb/s PAM4)
Length: 3 meters
Conductor Gauge: 26 AWG
Jacket: LSZH (Low Smoke Zero Halogen)
Protocol: 400GbE Ethernet
Standard: IEEE 802.3cd / 802.3bs class signaling
Condition: NEW — factory-sealed
Compatibility & Hard Constraints
Compatible with NVIDIA Spectrum-3 (SN4000) and Spectrum-4 (SN5000) switches and ConnectX-7 adapters operating at 400GbE. Requires ports configured for 400GbE PAM4 with appropriate FEC. Not compatible with QSFP56 200GbE ports without explicit auto-negotiation support; not a breakout cable to 8x50G SFP56 (use a QSFP-DD-to-8xSFP56 breakout SKU for that). Passive only; will not bridge longer reaches that require active or optical signaling. Fixed 3m length.
Why Choose T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS ships factory-sealed cables with full warranty. Handling time is 1-3 business days with global shipping and expert consultation on 400GbE fabric cabling.