Fill a 32-port 400G leaf switch with QSFP112 optics and the transceivers alone can draw roughly 256 to 384 watts with common 8\u201312 W modules. With higher-power long-reach optics approaching 13.5 W, the total can reach about 432 W. Nearly all of that electrical power ultimately becomes heat inside the rack. The switch PSU, PDU, airflow design and facility cooling system all have to absorb it.<\/p>\n\n\n\n
That is why a single QSFP112 power-consumption figure such as \u201c8 to 12 W\u201d is not enough for system planning. It does not tell you which variant fits a 500 m run, where the heat is generated inside the module, or what the rack will cost to operate over a year.<\/p>\n\n\n\n
This guide breaks down QSFP112 power consumption by module variant, explains the DSP-versus-optics contribution, discusses temperature and airflow constraints, and walks through watts-to-dollars calculations at pod scale. If you want the module fundamentals first, the complete QSFP112 400G guide covers speeds, variants and form factor.<\/p>\n\n\n\n
One scoping note up front: the methods for rack-power calculation, PDU sizing and generic thermal planning already appear in our QSFP28 and QSFP-DD power guides. This page focuses on QSFP112-specific numbers. Where the methodology is shared, we link to those guides instead of repeating it.<\/p>\n\n\n\n