StarTech.com Cisco QSFP-H40G-CU1M Compatible 1m 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

At £76.25 ex-VAT for a 1m twinax DAC, this is the kind of cable I’d usually only buy when the distance is short and you want to keep the spend sensible. Passive QSFP+ to QSFP+ links are ideal for stacking, top-of-rack to switch, or any “rack-neighbour” connectivity where you don’t want to pay for optics and don’t need the flexibility of fibre. In day-to-day use, the big win is simplicity: plug it in, it trains, it carries 40GbE reliably—assuming your vendor’s optics/cabling rules and your switch supports what it expects from that module.

Who should buy: anyone building a short run between QSFP+ ports in a homogenous Cisco-ish environment (e.g., within the same rack or adjacent racks) and wants a cost-effective, low-power copper solution. Who should *not* buy: if you’re hoping to solve a compatibility headache—“compatible” DACs can be great, but some environments are fussy (port defaults, optics policies, firmware behaviours). If you’re in a regulated/production setting where a single unexpected incompatibility is painful, I’d validate against your exact switch model/IOS and the specific port configuration before ordering a bulk batch. Overall: good value for short 40GbE copper, but I wouldn’t treat it as a universal “it’ll definitely work everywhere” part.