StarTech.com Juniper QFX-QSFP-DAC-3M Compatible 3m 40G QSFP+ to QSFP+ Direct Attach Cable Twinax - 40GbE QSFP+ Copper DAC 40 Gbps Low Power Passive Transceiver Module DAC

Product Overview

AI-generated summary

At £25.73 ex-VAT for a 3m passive 40G QSFP+ DAC, this is the kind of “just get it working” cable you buy when you’re staying inside the safe distance and you want solid value. Passive DACs like this are usually the sweet spot for short links between compatible switches and servers because they’re simpler, tend to run cool, and avoid the extra cost/points of failure you get with optics. If your setup is already built around QSFP+ and the link length is genuinely around 3m, it’s a practical, no-drama purchase.

That said, I’d be cautious if you’re unsure about vendor/QSFP+ compatibility—DACs can be picky, and if your switch expects a specific vendor’s module behaviour, you may get link issues or it may not come up cleanly. Also, passive copper at 40GbE doesn’t forgive distance creep; if your route is a bit longer than planned or you’re dealing with extra slack/poor cable management, you’ll regret it. Who should buy: teams doing short, fixed 40G connections (rack-to-rack within a few metres) who want predictable performance on a budget. Who shouldn’t: anyone chasing long runs, flexible routing, or without confirmed compatibility.