StarTech.com Cisco QSFP-H40G-ACU5M Compatible 5m 40G QSFP+ to QSFP+ Direct Attach Cable Twinax - 40GbE QSFP+ Copper DAC 40 Gbps Low Power Active Transceiver Module DAC Firepower ASR1000 ASR9000

Product Overview

AI-generated summary

For £94.74 ex-VAT, this is one of those “it’ll probably be fine, but you’re buying confidence” DAC-style cables. The upside is straightforward: it’s ideal if you’re dropping short-range 40GbE links between compatible switches/routers and you want low power, low latency, and a tidy rack setup without the faff (and cost) of optics. In real day-to-day B2B work, these are most worth it when the link length is genuinely short and you’ve verified your vendor’s compatibility—because DACs are less forgiving than “looser” networking gear.

Who should buy: teams standardising internal 40GbE point-to-point connections (e.g., switch-to-switch, switch-to-server) where you can keep runs in the right distance range and you don’t need reach. Who should avoid: anyone who’s not sure about platform/QSFP+ compatibility, or who might later repurpose the cable across different hardware models—active copper modules can behave differently depending on how the endpoints negotiate. If you’ve got any doubt, it’s worth checking compatibility first; otherwise you may end up wasting time on replacements rather than saving money on the cable.