BM1397

BM1397 is Bitmain's 7 nm SHA-256 mining ASIC (silicon chip ID 0x1397), the second-generation die introduced in 2019 that powers the entire air-cooled Antminer S17 and T17 line. It computes the double-SHA-256 hashes that Bitcoin's proof-of-work depends on, and it marked Bitmain's move to a 7 nm process after the 16 nm and earlier nodes of the S9/S15 era.

Where the BM1397 is used

The BM1397 is the production driver for the whole S17/T17 base and "e" generation. The same die sits inside the S17, the S17 Pro, the T17, and the higher-efficiency S17e and T17e models. Across all of these, only the firmware tuning targets and bin grades differ; the underlying silicon is the same 7 nm chip carrying the 0x1397 ID.

One persistent mistake is worth clearing up: older references sometimes credit the S17 generation to a "BM1393." That is incorrect. BM1393 is a named-only chip associated with the S9j family, not the S17. The S17/T17 generation runs on the BM1397, which is the registered, documented driver for 0x1397 (confirmed in the chip genealogy and hardware-reference records). Note also the closely related BM1396, the die used in the S17+ and T17+ "Plus" units. The BM1396 and BM1397 share the same 0x51/0x41 command-header family and are register-compatible, but they are distinct chip IDs — firmware dispatches on the chip's address word, so a BM1396 board should never be cross-populated onto BM1397 hardware.

What the silicon looks like

Each BM1397 contains roughly 672 hashing cores and communicates over the standard Bitmain serial chain using the 0x51/0x41 command-header protocol. On a stock S17 hashboard, 48 BM1397 chips are wired in a single serial string, and the board is divided into 12 voltage domains of 4 chips each. Each domain runs at roughly 1.55 V, with the domains stacked in series so the control board manages current across groups of four chips rather than one chip at a time. A complete S17 carries three of these boards driven by a Xilinx Zynq-7010 control board.

Power, efficiency, and tuning

Per-chip throughput lands in the ~166–200 GH/s range depending on model and clock, and wall-plug efficiency spans roughly 40–55 J/TH across the generation — the S17+ sits near 40 J/TH, the base S17 around 45 J/TH, and the T17 closer to 55 J/TH. Because the chip exposes a tunable PLL frequency and a per-domain voltage, custom firmware can walk these operating points to chase efficiency, peak hashrate, or a fixed power envelope. The S17 generation arrived just as autotuning firmware matured, so much of the practical efficiency on these boards comes from runtime frequency/voltage curves rather than fixed factory presets.

Why it matters for repair and diagnostics

The BM1397 is one of the most thoroughly studied mining ASIC chips, with openly documented register behavior (the Mujina reverse-engineering work covers this family in detail), which makes board-level diagnostics on S17 hardware unusually approachable. That openness matters because the S17 generation was notorious for thermal-stress failures: cracked solder joints, dead domains, and chips that pass a quick power-on but fail under sustained load. Harvested BM1397 dies are also among the most heavily recycled on the used market, so a board advertised as "tested working" still warrants a full bench check — verify every domain's voltage, look for a chip count short of 48 on the chain, and confirm the hashboard holds rate under thermal load before trusting it.

In practical terms, the BM1397 is the chip you are servicing whenever you open an S17- or T17-class Antminer. Knowing its 48-chip chain, 12-domain layout, and per-domain voltage lets you reason about a dead or under-hashing board at the domain level instead of guessing. For a look at the newer end of the same lineage, the BM1368 entry covers the current S21-generation silicon, and our miner catalog lays out where each chip generation lands across the Antminer family.