ASIC Fan Specification & Wiring Reference
Fan specification and wiring reference for Bitcoin ASIC miners — per model/family: fans per unit, fan form factor, supply voltage, the 4-pin PWM connector, measured RPM behaviour and the linked fan-speed / fan-missing error class, grounded in the D-Central Mining Bible.
Quick answer
This reference catalogs the cooling fans on 9 Bitcoin ASIC miner models/families — the Antminer S9 (2 fans), S17 / T17, S19 / T19, S21 / T21 and S23 generations (4 fans), the L3+ / L7, MicroBT WhatsMiner M-series (2 fans) and the Innosilicon T2Tz (two 12038 fans) — plus the shared 4-pin chassis fan-header electrical pinout (pin 1 GND, pin 2 +12V, pin 3 tachometer, pin 4 PWM). Every row lists fans per unit, fan form factor, 12V supply, the connector, measured RPM behaviour and the minimum-fan / fault floor, and links the matching fan-speed / fan-missing error code.
The Bitcoin-mining standard is a 120 mm-class, 12V, 4-pin PWM fan with tachometer feedback, driven by the CONTROL BOARD (not the PSU). Free CSV/JSON under CC BY 4.0. Honest scope: airflow (CFM) and several per-model fan sizes are not published in our verified sources and are flagged "unverified" rather than guessed — always confirm the actual fan and pin keying on your unit before wiring, and never power a hash board without airflow.
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Antminer S9 / S9i / S9j BM1387
| Fans per unit | 2 (dual) |
|---|---|
| Fan size | 120 mm class (12038 form factor) — per-model thickness not separately verified in the Bible |
| Voltage | 12 V DC |
| Connector | 4-pin (GND / +12V / tach / PWM) |
| RPM | Bench-measured 1,920–2,220 RPM at the ~10% PWM quiet floor; ramps to full under load (controller FULL_SPEED = 100%). ~120 RPM per tach counter unit. |
| Min-fan / fault | Stock firmware requires 2 working fans to start |
| Airflow (CFM) | Not specified in the Bible — unverified |
| Error class | fan-speed / fan-missing |
Related error codes: Antminer S9 — Fan Speed Error
The S9 control board (Zynq FPGA) exposes only two fan-tach registers — the upper two always read zero because the S9 has two fans. Speed is read back via the FPGA fan_rps registers (×60 → RPM).
Source: FPGA_REGISTER_MAP.md (FAN_RPS registers); HASHBOARD_DIAGNOSTICS.md §11.4–11.5; S9 home-bench live capture (2026-05) · last verified 2026-06
Antminer S17 / S17 Pro / S17+ / T17 / T17+ BM1397 (S17/T17 generation)
| Fans per unit | 4 |
|---|---|
| Fan size | 120 mm class (12038 form factor) — per-model thickness not separately verified in the Bible |
| Voltage | 12 V DC |
| Connector | 4-pin (GND / +12V / tach / PWM) |
| RPM | Bench-measured 2,760–3,600 RPM across the four fans (≈28% PWM, ~447 W/board) |
| Min-fan / fault | Not separately specified — unverified |
| Airflow (CFM) | Not specified in the Bible — unverified |
| Error class | fan-speed / fan-missing |
Related error codes: Antminer S17 — Fan Speed Error
Four independent fan-tach channels (vs two on the S9). The control board drives all four through the FPGA PWM block; live probes show fan_num = 4.
Source: S17_VNISH_FIRMWARE_RE_ANALYSIS.md; S17_VNISH_LIVE_PROBE.md (fan_num: 4); HASHBOARD_DIAGNOSTICS.md §11.4 · last verified 2026-06
Antminer S19 / S19 Pro / S19j / S19j Pro / S19 XP / S19k Pro / T19 BM1362 / BM1366 / BM1396 (S19 generation)
| Fans per unit | 4 (two PWM channels: front pair + rear pair) |
|---|---|
| Fan size | 120 mm class (12038 form factor) — per-model thickness not separately verified in the Bible; stock units use 120 mm or 140 mm fans |
| Voltage | 12 V DC |
| Connector | 4-pin (GND / +12V / tach / PWM) |
| RPM | Bench-measured ~3,810–3,840 RPM in stock auto mode; ~2,160–2,700 RPM at 60% PWM; ~4,140–4,260 RPM at 45% PWM; split-duty operation runs the front pair ~1,500 RPM and the rear pair ~5,800 RPM. Amlogic-platform units boot both groups to 100% PWM (~6,500 RPM blast) during init. |
| Min-fan / fault | Common third-party firmware enforces a ~2,000 RPM minimum-fan floor; a fan reading <500 RPM when >2,000 is expected trips the fan-failure alarm |
| Airflow (CFM) | Not specified in the Bible — unverified |
| Error class | fan-speed / fan-missing |
Related error codes: Antminer S19 — Fan Speed Error · Antminer T19 — Fan Speed Error
The S19 generation drives four fans on two PWM channels — the front and rear pairs can run at different duties. Control boards expose a front/rear split (single-channel vs dual-channel board mode); both must be enabled to control all four fans quietly.
Source: MASTER_FAN_CURVES.md §2.5; S19_BRAIINSOS_DEEP_PROBE; AM2-FAN-CONTROL-CROSS-FIRMWARE.md; HASHBOARD_DIAGNOSTICS.md §11.4 · last verified 2026-06
Antminer S21 / S21 Pro / S21 XP / S21+ / T21 BM1370 / BM1366 (S21 generation)
| Fans per unit | 4 (air-cooled; two PWM channels) |
|---|---|
| Fan size | 120 mm class (12038 form factor) — per-model thickness not separately verified in the Bible |
| Voltage | 12 V DC |
| Connector | 4-pin (GND / +12V / tach / PWM) |
| RPM | Amlogic-platform units boot both fan groups to 100% PWM; deep-probe captures show 100% duty on the front and rear groups during init before the controller ramps down to target temperature. Steady-state RPM not separately tabulated — unverified. |
| Min-fan / fault | Minimum-fan count is configurable (lab/immersion probes seen with min_fans = 0) |
| Airflow (CFM) | Not specified in the Bible — unverified |
| Error class | fan-speed / fan-missing |
Related error codes: Antminer S21 — Fan Speed Error · Antminer T21 — Fan Speed Error
Safety-critical: on the S21 XP, continuous bench pattern-testing with NO fan causes chip burnout — never power a hash board without airflow. The S21 control board is the Amlogic AXG platform (SoC PWM channels 0/1).
Source: MASTER_FAN_CURVES.md §2.5/§3; S21_BRAIINSOS_DEEP_PROBE.md; HASHBOARD_DIAGNOSTICS.md §11.5 · last verified 2026-06
Antminer S23 (2026) BM1373
| Fans per unit | 4 (air-cooled) |
|---|---|
| Fan size | Not separately specified in the Bible — unverified |
| Voltage | Not separately specified for the S23 — unverified (the Antminer chassis-fan standard is 12 V, 4-pin) |
| Connector | Standard 4-pin assumed — not separately verified for the S23 |
| RPM | Not specified in the Bible — unverified |
| Airflow (CFM) | Not specified in the Bible — unverified |
| Error class | fan-speed / fan-missing |
S23: 318 TH/s, 3,498 W, ~11.0 J/TH, air-cooled with 4 fans, January 2026. Fan electrical/RPM specifics are not yet documented in the Bible — included for completeness and flagged as unverified.
Source: BM1373_S23_RESEARCH.md · last verified 2026-06
Antminer L3+ / L7 (Scrypt) BM1485 (L3+) / BM1489 (L7)
| Fans per unit | Multi-fan — exact count per model not separately specified in the Bible (unverified) |
|---|---|
| Fan size | 120 mm class — per-model not separately verified in the Bible |
| Voltage | 12 V DC |
| Connector | 4-pin (GND / +12V / tach / PWM) |
| RPM | Not directly tabulated. The L3+ control board (BeagleBone-class) drives fan PWM at 10 kHz with a 50% boot duty. |
| Min-fan / fault | L7 firmware carries a configurable max-RPM sanity bound used as the fan-failure threshold |
| Airflow (CFM) | Not specified in the Bible — unverified |
| Error class | fan-speed / fan-missing |
Related error codes: Antminer L7 — Fan Speed Error
The L3+ uses a 10 kHz fan-PWM carrier (vs 25 kHz on some others), fixed by the control-board peripheral — replicate the frequency or the fans stall. L7 fan control is fully firmware-managed.
Source: MASTER_FAN_CURVES.md §2.3, §2.4 · last verified 2026-06
WhatsMiner M30S / M50S / M60S (BT1000-class control board) MicroBT K-series
| Fans per unit | 2 (dual) |
|---|---|
| Fan size | Not specified in the Bible — unverified |
| Voltage | Not separately specified in the Bible — unverified |
| Connector | 4-pin PWM (SoC-driven fan path) |
| RPM | Firmware fan curve interpolates 0% PWM → ~30 RPM (idle), 10% → ~600 RPM, 100% → ~5,000 RPM (BT1000-class) or ~5,800 RPM (H6-class control board). Over-temp kill at 105 °C (BT1000) / 100 °C (H6). |
| Min-fan / fault | Fan speed is coupled to chip frequency via a configured scaling factor |
| Airflow (CFM) | Not specified in the Bible — unverified |
| Error class | fan-speed / fan-missing |
Related error codes: Whatsminer M30S — Fan Speed Error · Whatsminer M50S — Fan Speed Error · Whatsminer M60S — Fan Speed Error
WhatsMiner is the only platform that publishes explicit PWM→RPM nodes in plaintext config; the curve is linearly interpolated between the three nodes. Included as a cross-vendor reference.
Source: MASTER_FAN_CURVES.md §2.15–§2.16 · last verified 2026-06
Innosilicon T2Tz Innosilicon SHA-256 (T2 family)
| Fans per unit | 2 (dual) |
|---|---|
| Fan size | 12038 (120 × 120 × 38 mm) — explicitly documented for this model in the Bible |
| Voltage | 12 V (standard for the 12038 form factor) — not separately stated for this model |
| Connector | 4-pin (GND / +12V / tach / PWM) |
| RPM | Factory firmware ships fan-mode = manual at 100% fixed duty; auto mode targets 65 °C chip temp with critical shutoff at 90 °C. RPM range not separately specified — unverified. |
| Min-fan / fault | Auto mode targets 65 °C chip; critical chip temp 90 °C |
| Airflow (CFM) | Not specified in the Bible — unverified |
| Error class | fan-speed / fan-missing |
30 TH/s SHA-256 BTC miner, ~2,200 W, 3 hash boards, two 12038 fans (~2018–2020 era). This is the one model where the Bible names the exact fan size.
Source: T2TZ_3_1_9_RE.md; MASTER_FAN_CURVES.md §2.14 · last verified 2026-06
Chassis fan header — electrical reference (all Antminer generations)
| Voltage | +12 V DC (from the PSU OUT2 auxiliary rail) |
|---|---|
| Connector | 4-pin: pin 1 GND, pin 2 +12 V, pin 3 tach (open-collector RPM-sense pulse), pin 4 PWM (speed control). Repair fixtures accept KF2510 4/6-pin and Molex 5557 4-pin housings. |
| RPM | Tachometer pin returns RPM to the control board; PWM duty sets speed |
| Error class | fan-speed / fan-missing |
Related error codes: ASIC Fan Error or Fan Noise — Troubleshooting
Chassis fans are driven by the CONTROL BOARD, not the PSU. On Zynq control boards the FPGA generates fan PWM and reads the tachometer; on Amlogic boards the SoC PWM channels (0,1) do it. PSU-internal fans are governed by the PSU's own circuitry and are not exposed to the control board. The PWM carrier is typically 10 kHz (Amlogic / BeagleBone) but 1 kHz on some stock Cvitek boards — match the board. Never hot-plug a fan or signal cable while power is applied.
Source: HASHBOARD_DIAGNOSTICS.md §11.4–11.5; ANTMINER_ARCHITECTURE.md; MASTER_FAN_CURVES.md §1 · last verified 2026-06
Grounded in the D-Central Mining Bible (HASHBOARD_DIAGNOSTICS, ANTMINER_ARCHITECTURE, MASTER_FAN_CURVES, FPGA_REGISTER_MAP and per-model live probes) — a fan-spec reference, no security or exploit detail. Pairs with the connector pinout reference, the cooling comparison and the fan-error troubleshooting guide. Verify the actual fan and pin keying against your specific unit before wiring.
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Last reviewed June 22, 2026.