Identity & Definition
The HP 670759-B21 is a passive copper direct-attach cable (DAC) in the enterprise InfiniBand interconnect category. This is a 0.5-meter FDR InfiniBand cable with QSFP connectors on both ends, operating at 56 Gb/s (4x 14 Gb/s lanes). This is a fixed-length integrated cable assembly, not a transceiver with a detachable patch cord. This is an InfiniBand-rated cable, not an Ethernet-specific cable. Condition: Refurbished.
Engineering Context
At 0.5 meters, this cable is designed for same-rack or adjacent-rack-unit connections where latency and airflow density matter most. The passive design provides the lowest possible latency (no signal processing delay) and zero additional power consumption compared to active optical cables (AOCs). Passive copper signal integrity at FDR (56 Gb/s) limits maximum reach to approximately 2–3 meters; at 0.5 m, signal margin is substantial. The 4x 14 Gb/s lane configuration uses 64b/66b encoding. HP spare part number 670759-B21.
Deployment & Use Cases
Same-rack InfiniBand FDR connections between compute nodes and top-of-rack switches in HPC clusters. Switch-to-switch short-distance interconnects within modular chassis systems such as the SX6506 or SX6512. Intra-rack GPU clustering where sub-microsecond latency and minimal cable bulk are critical. HP ProLiant and Apollo server deployments with Mellanox ConnectX-3 Pro or ConnectX-4 adapters running FDR InfiniBand.
Technical Specifications
OEM: HP
Part Number: 670759-B21
Speed: FDR InfiniBand (56 Gb/s)
Cable Type: Passive Copper (DAC)
Length: 0.5 meters
Connector: QSFP to QSFP
Lanes: 4x 14 Gb/s
Protocol: InfiniBand FDR
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Hard Constraints
InfiniBand FDR only — this cable operates at 56 Gb/s. It does NOT support EDR (100 Gb/s), HDR (200 Gb/s), or NDR (400 Gb/s). Connecting to EDR/HDR/NDR ports will result in negotiation down to FDR at best, or link failure. The QSFP connectors are physically compatible with QSFP+ and QSFP28 ports, but the cable operates at FDR speed only. This is a fixed 0.5 m length — it cannot be extended. For longer distances at FDR, use active optical cables (AOCs) or fiber with QSFP transceivers. HP-branded cable accepted by HP and Mellanox/NVIDIA equipment; some third-party switches may require MSA-compliant cable verification. Predecessor: QDR (40 Gb/s) cables. Successor: EDR (100 Gb/s) passive copper DACs.
Why Choose T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS (tes-itsolutions.com) tests every cable for link integrity and signal quality before shipping. Technical consultation is available for fabric cabling design and speed/reach planning. Global shipping with 1–3 business day handling.