Bitaxe Gamma

The Bitaxe Gamma is an open-source, single-chip Bitcoin solo miner built around one Bitmain BM1370 ASIC — the same TSMC 5 nm silicon that powers the Antminer S21 Pro. It delivers roughly 1.2 TH/s of SHA-256 hashrate from a palm-sized board that sips about 18 watts off a 5 V barrel jack, making it the most efficient member of the Bitaxe family to date.

One S21 Pro chip on your desk: the BM1370

Where a full-size Antminer spreads dozens of ASICs across three hashboards, the Bitaxe Gamma does the opposite: it puts a single BM1370 on one small PCB and gives that chip a control board the size of a credit card. The BM1370 is Bitmain’s Gen-5 « Pro » silicon, fabricated on a TSMC 5 nm process (not 3 nm — a common spec-sheet error). Internally it carries 1,280 hashing cores, organised as 80 large cores each containing 16 small cores, the identical core layout used in the S21 Pro’s high-density hashboards. On a stock Antminer that chip is one of 220-plus on a chain; on the Gamma it is the whole show.

The « control board » here is not a Xilinx Zynq SoC running embedded Linux, as on a commercial Antminer. Instead an Espressif ESP32-S3 microcontroller drives the ASIC directly over a UART serial link (TX on GPIO 17, RX on GPIO 18), starting at 115,200 baud and switching to 1 Mbaud once the chip is initialised. The ESP32 speaks the same BM13xx wire protocol Bitmain uses internally — 0x55 0xAA framed packets, CRC-5 for commands and CRC-16 for jobs — so the Gamma is, in effect, a faithful miniature of an S21 Pro hashboard with a hobby-friendly brain.

Two architectural details are worth knowing. First, the BM1370 uses full-block-header jobs: the host hands the chip the raw header and the ASIC computes the SHA-256 midstate itself, which keeps the ESP32’s workload light. Second, the chip does hardware version rolling (AsicBoost) natively — the firmware writes a version mask to register 0xA4 and the BM1370 grinds through up to 65,536 version permutations per job on its own. Voltage is delivered by a single on-board TPS546 buck regulator feeding the chip’s core rail; unlike a multi-board Antminer there is one regulator and one voltage domain to worry about, and (as on all S21-generation silicon) there is no PIC chip gatekeeping the board.

Real-world power and efficiency

Nameplate numbers and wall numbers are not the same thing, and on a single-chip board the gap matters more than on a 3,500 W Antminer. At its stock tune the Gamma produces roughly 1.2 TH/s for about 18 watts at the wall, which works out to roughly 15 J/TH. That figure is unusually good for such a small device because the BM1370 silicon itself is genuinely efficient — in its native S21 Pro habitat it operates near 15 J/TH.

The catch is fixed overhead. A single-chip board still has to power an ESP32, a cooling fan, and regulator losses, and those watts do not scale down. Push the BM1370 harder through the firmware’s frequency and voltage controls and total draw climbs toward 18-21 watts as you trade efficiency for hashrate; back it off and you can shave watts at the cost of terahashes. There is real tuning headroom here, and because the autotuner calculates its operating point at runtime rather than reading a fixed preset, two Gammas on the same desk can settle at slightly different frequencies depending on silicon quality and airflow. If you want to understand where a given frequency/voltage pair lands on the efficiency curve before you dial it in, our ASIC power profiles database maps the trade-offs for the BM1370 generation.

One honest note on heat: at ~15 watts the Gamma emits only about 61 BTU/h. That is a warm paperweight, not a space heater — meaningful room heating is the job of the multi-kilowatt Antminers, not a desktop Bitaxe. Treat the Gamma’s warmth as a pleasant side effect, not a heating strategy.

Firmware compatibility

The Gamma ships running AxeOS, the web UI on top of the open-source ESP-Miner firmware (the bitaxeorg/ESP-Miner project). It is written in C on ESP-IDF, exposes a clean local web dashboard for hashrate, temperature, and pool status, supports over-the-air updates, and can be flashed straight from a browser. AxeOS handles both pooled mining and true solo mining, pointing at a public pool, a solo pool, or your own Bitcoin node.

Be clear-eyed about the protocol: AxeOS talks Stratum V1. Among ASIC firmwares only Braiins’ BraiinsOS+ natively speaks Stratum V2, so if you want V2’s template negotiation on a Bitaxe you run it through a V2-to-V1 translating proxy rather than expecting the board to do it itself. The « third-party firmware » landscape that surrounds big Antminers (VNish, LuxOS and the like) simply does not apply to a single-chip ESP32 board — on the Gamma, ESP-Miner essentially is the firmware ecosystem, with forks such as the NerdAxe and NerdQAxe branches targeting multi-chip cousins rather than the stock single-chip board. D-Central develops its own GPL-3.0 open-source axe firmware in the same spirit of the project — currently in closed beta, with a public beta planned for summer 2026 — building on the shoulders of skot and the ESP-Miner contributors rather than replacing them. For first-boot Wi-Fi provisioning and pool configuration, follow our Bitaxe setup guide.

Common faults and troubleshooting

Because the Gamma exposes one chip and a handful of support components, faults are easy to localise once you know the symptom map:

• Board won’t power on — almost always the 5 V supply or barrel jack. The Gamma needs a clean 5 V/≥3 A source; thin or under-rated USB adapters cause brownouts. See Bitaxe won’t power on.
• Powers on but zero hashrate / « 0 ASIC found » — a UART or chip-detection failure, often a cold solder joint on the ASIC or a stalled init sequence. Walk it through Bitaxe not hashing.
• Overheating or thermal throttling — the BM1370 packs S21 Pro density into a tiny heatsink, so airflow and VRM cooling are critical. A failing fan or a hot TPS546 will throttle frequency fast; see Bitaxe overheating & VRM.
• Won’t join the network — the Gamma is 2.4 GHz Wi-Fi only; 5 GHz-only SSIDs are the usual culprit. See Bitaxe Wi-Fi troubleshooting.

For anything that does not fit a single symptom, our interactive ASIC fault finder walks you from observation to likely cause, and the Bitaxe board anatomy reference helps you find the regulator, fan header, and ASIC at a glance.

Repair and longevity

A single-chip board is forgiving in one way and unforgiving in another: there is far less to diagnose than on a 200-chip hashboard, but every component is load-bearing — if the one BM1370 dies, the miner stops. D-Central has repaired ASIC hardware in-house in Laval since 2016, and the same bench skills that bring Antminer hashboards back to life apply to a Gamma: BM1370 reflow or replacement, TPS546 regulator swaps, barrel-jack and fan-header rework, and reading the chip’s domain hash counters (registers 0x88-0x8B) to confirm the silicon is healthy after a fix. Run cool and clean, a Gamma will hash for years; run it pinned at maximum voltage with a tired fan and you will shorten the regulator’s life. If you have a dead or flaky unit, start with our Bitaxe repair diagnostics, get a ballpark from the ASIC repair cost estimator, or send it to our ASIC repair service.

Who the Gamma is for — and how to buy

The Bitaxe Gamma is not a profit machine, and it is honest to say so. One unit’s ~1.2 TH/s is a rounding error against the network’s exahash, so the economics are a solo-mining lottery ticket: point it at your own node or a solo pool and you are buying a small, perpetual chance at a full block reward while learning exactly how Bitcoin mining works end to end. That makes it ideal for sovereign-minded Bitcoiners who want to mine on their own terms, for tinkerers who want a fully open KiCad/firmware platform to modify, and for anyone teaching themselves the protocol. If you are weighing it against the previous generation, our Bitaxe Gamma vs Supra comparison breaks down the BM1370-versus-BM1368 jump. Canadian buyers can see current stock on the buy a Bitaxe in Canada page, explore the wider open-source range on the Bitaxe hub, and cross-shop full specs in our ASIC miner database.

Generational context

The Bitaxe line was created by skot as the first fully open-source Bitcoin ASIC miner — hardware and firmware both public — and the community has since deployed well over 100,000 units and found multiple solo blocks with them. The Gamma sits at the top of that lineage, each generation tracking whichever Bitmain chip was current:

Two things make the Gamma the standout. It roughly doubles the hashrate of the BM1368-based Supra while improving efficiency, and it puts genuinely current data-centre silicon — the same chip Bitmain reserves for its flagship air-cooled S21 Pro — into a device anyone can own, flash, and repair. Multi-chip relatives built on the same BM1370 (the Gamma Duo, the Gamma Turbo, and community boards such as the NerdQAxe++ and NerdOctaxe) scale the idea up to several terahash, but for a single chip on a single 5 V supply, the Gamma is the most capable open-source Bitcoin miner you can put on a desk today. We build on the work of skot, the ESP-Miner contributors, and Bitmain’s silicon teams — the Gamma is decentralisation made tangible, one open-source ASIC at a time.