{"id":19428,"date":"2026-05-25T07:21:40","date_gmt":"2026-05-25T07:21:40","guid":{"rendered":"https:\/\/www.fibermall.com\/blog\/?p=19428"},"modified":"2026-06-03T08:56:26","modified_gmt":"2026-06-03T08:56:26","slug":"qsfp28-dac-vs-aoc-choosing-the-right-100g-cable-2026-guide","status":"publish","type":"post","link":"https:\/\/www.fibermall.com\/blog\/qsfp28-dac-vs-aoc-cable-guide.htm","title":{"rendered":"QSFP28 DAC vs AOC: Choosing the Right 100G Cable (2026 Guide)"},"content":{"rendered":"\n

One bad cable decision cost a team $40,000.<\/p>\n\n\n\n

They were building a new data hall. Forty-eight racks, two leaf switches per rack, every server connected at 100G. The engineer specified QSFP28 AOC cables for every single link.<\/p>\n\n\n\n

Same rack. Adjacent rack. Everywhere.<\/p>\n\n\n\n

Three months later, the power audit came back. Those AOCs were drawing 800 watts more than passive DACs would have. The extra power meant they needed another PDU per rack. Total cost of that one decision? About $40,000 in cabling, power infrastructure, and cooling overhead.<\/p>\n\n\n\n

A $25 passive DAC would have handled most of those links just fine.<\/p>\n\n\n\n

\"QSFP28<\/figure>\n\n\n\n

Choosing between QSFP28 cable types isn’t complicated, but most guides get it wrong. They treat “DAC” as one thing. They ignore active DAC entirely. And they never show you the rack-level math that actually drives the decision.<\/p>\n\n\n\n

This guide covers the three real QSFP28 cable options \u2014 passive DAC, active DAC, and AOC \u2014 with a distance-based selection matrix that tells you exactly what to buy. If you’re planning a 100G spine-leaf design<\/u><\/a> or just connecting servers to a ToR switch, here’s what actually matters.<\/p>\n\n\n\n

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