StarTech.com Cisco QSFP-H40G-CU3M Compatible 3m 40G QSFP+ to QSFP+ Direct Attach Cable Twinax - 40GbE QSFP+ Copper DAC 40 Gbps Low Power Passive Transceiver Module DAC Firepower C9200 C9400

Product Overview

AI-generated summary

For £24.11 ex-VAT, this is the kind of sensible “get the job done” copper DAC you buy when you already know your switch-to-switch (or switch-to-server) distance is within spec and you don’t need the flexibility of optics. The big win with passive 40G QSFP+ DAC is power/latency and, in practice, it’s usually plug-and-play in a lot of Cisco-ish environments—especially for short rack-to-rack runs where spending on optics feels like overkill. If you’re doing predictable 40GbE interconnects between nearby devices, it’s good value and tends to be trouble-free.

I’d avoid it if you need longer runs, slightly different connector/pinning expectations, or you’re trying to standardise across a mixed fleet where compatibility quirks matter. Because it’s a “compatible” module, you’re relying on vendor interoperability rather than full Cisco-branded certainty—still often fine, but it’s not the best choice for environments that are strict about optics/DAC validation. In short: buy it if your cabling distance is correct and you want low-cost, low-hassle 40G copper; don’t buy it if you need maximum interoperability assurances or you’re near the limits on reach.