Antminer S9 Underclock
The honest answer to “S9 underclock settings”: there is no watt target to set. The S9 is the one model on this page where “there are no presets” is literally true at the firmware level: S9-era firmware has no profile system at all — you set frequency (and on stock firmware, voltage) yourself. The bands below are community planning references, marked Supported, not extracted presets. That distinction is the whole point of this page.
Quick answer
The Antminer S9 tunes across a 850–1,650 W envelope (Normal mode: 10–17 TH/s). Best catalog efficiency is 85.0 J/TH, and the sweet spot — everything within 5% of it — spans 850–1,150 W. The floor is 850 W — 63% of the 1,350 W factory rating. There are no frequency/voltage settings to copy: you set a watt target and the firmware autotuner derives the rest for your unit. Status: Supported.
Best efficiency sits at or near the envelope floor: the lowest watt target your hashrate goal tolerates is also the most efficient point in the catalog.
Antminer S9 — Normal mode Supported
Floor fits a 120 V 15 A continuous-load budget (1,440 W). Budgets are the NEC 80% continuous-load rule; circuit fit only — stock Bitmain APW-series PSUs require 200–240 V input, so any 120 V build needs a PSU change regardless of watt target. At the floor this mode dissipates about 2,900 BTU/h (watts × 3.412).
Source: Community reference points, theme catalog only. S9-era firmware has no factory preset profiles: frequency and voltage are user-set, so these points are planning bands from community charts, not extracted presets.
How to set a power target on this model
Aftermarket firmware exposes underclocking as a power target (sometimes "power limit" or a preset picker), not as frequency/voltage fields. Pick a watt figure inside the envelope above; the autotuner benchmarks your boards and settles onto it over a tuning period. Braiins OS+, VNish and LuxOS each expose this in their own UI, and DCENT_OS uses watt-target autotuning on its supported models; the undervolting guide walks through the firmware side step by step, and the firmware comparison covers which firmware supports which model. Verify the result at the wall with a meter — the target is an input, the wall draw is the fact.
- Braiins OS+ — set a power target →
- VNish — pick a preset →
- Stock firmware modes →
- LuxOS power targeting →
Frequency and voltage are calculated at runtime by the firmware autotuner — never fixed presets; per-unit silicon quality, ambient temperature and cooling shift real results.
These envelopes are derived aggregates (bounds, bands, counts) — the row-level operating points, the interactive picker and the CSV/JSON of the source data live in the ASIC Power Profiles Database, the single source dataset for every number on this page.
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Last reviewed August 13, 2026.