Bitmain chips in Antminer miners

01Why the chip marking matters

The chip is the one part of a miner with no substitute. Fans swap out. A power supply can be picked by connector and wattage, a control board replaced with a close relative from the same generation. The chip is either the right one or the board never starts.

In practice the marking matters in four situations. Buying used: the generation tells you the age of a machine more honestly than the seller does, and it sets a hard ceiling on efficiency. Ordering spares: BM1368PA and BM1368AA are different parts, and marketplace listings do not always say so. Repairing a hash board: the chip sets the domain layout, which is where you start looking for the break. And choosing firmware: custom build support follows the die generation as much as the model name.

The marking also helps when a machine turns up with no box and no stickers. Five minutes with a magnifier over the hash board saves the whole back and forth with the seller.

02How to tell which chip you have

Four ways, from the quickest to the most reliable.

By model

Works nine times out of ten. Find your machine in the tables below and read off the marking. Be careful where Bitmain changed the internals under one name: the S19j Pro went through several board revisions across two years of production, and the S21 XP carries BM1370P instead of the plain BM1370.

By the print on the chip itself

The most direct route and the only one that is certain. The marking sits on the top face of the package and reads under a magnifier with light coming in from the side. The catch is that on air cooled machines the chips are under heatsinks, and pulling those off out of curiosity is a bad idea: the adhesive holds hard, and a chip cooked with a hot air gun comes away with its pad. If the board is already apart for repair, look, and look at the suffix too.

By the hash board code

The code is printed on the PCB, usually near the edge next to the connector. It is tied to the generation more tightly than the model name is.

By the miner log

On the kernel log tab of the web interface the machine reports how many chips it found on each chain. A line like "Chain 1 has 126 asics" is your configuration. Not every firmware prints the chip type there, but the count alone narrows things to one or two options: 126 only happens on the S19j Pro, 108 only on the S21 series.

03Bitcoin chips: fifteen generations

Bitmain designs the die in house and prints at TSMC. The pace is roughly one new chip every eighteen months, and the win each time is joules per terahash rather than raw hashrate. The useful starting point is BM1387: the S9 chip that made Antminer the industry standard in 2016 and still turns up working wherever power is cheap.

Two caveats about the table. The process node column does not come from manufacturer documentation: Bitmain lists nanometres in none of its official specifications, so the figures are reconstructed from press releases and teardowns. TSMC is directly confirmed only for BM1385, BM1387, BM1393, BM1397 and BM1366. For the rest the foundry is a reasonable guess rather than a fact.

BM1396 stands apart in this list. There was never a public announcement. It is known only from repair databases, which all name BM1396AB as the chip on S17e and T17e boards. The 17 series as a whole came out badly: it runs hot, hash boards die often, and the used market takes it reluctantly.

04Chips per board and what a domain is

Chips on a hash board are wired into a chain and powered in groups. A group is called a domain: inside a domain the chips sit in series and share one voltage, and the domains themselves run in series with each other. The notation "42 × 3" means forty-two domains of three chips, 126 on the board.

From which follows the main rule of diagnostics: one chip burns out and the whole domain goes with it, because the chain is broken. The miner will not tell you "chip 71 is dead", it will show a third of the hashrate gone or the board missing entirely. The same logic drives the recent generations: more chips, lower frequency and voltage. The S19j Pro gets the same efficiency out of 378 chips that the S19 Pro gets out of 342, with less stress on each die.

S19 series and newer

From the S1 to the 17 series

The spread is wider than it looks: 30 chips per board on the T17 and 135 on the S17e are one generation a year apart. Bitmain was experimenting with density in those years, and the S17e board, at 405 chips per machine, still holds the record for sheer count.

05Chips for the other algorithms

For Litecoin, Kaspa, Dash and the rest Bitmain publishes almost nothing. The markings come from repair shops and parts sellers: if a chip is sold on its own for one specific model, that is the chip inside it. Years in the table are the year the miner shipped, not the date the die was ready.

Three things people get wrong here. The Z15 hash board carries three chips in total, and that is not a typo: the die is large and each one has its own power stage. The L7 chip sells under two names, BM1489 and B20, one part with two markings. And KS3L and KS3M, which come up next to the KS3 in search, have nothing to do with Bitmain, they are IceRiver models.

06Process node: what is known and what is invented

Here comes the unpleasant part. Most of the "ASIC chip reference" tables that search returns contradict each other, and some are assembled automatically and simply make things up. We went through the disputed entries one by one, trying to disprove them rather than confirm them. Here is what did not survive.

BM1362 is not 5 nm

Plenty of sources repeat the 5 nm claim, but the dates do not line up: TSMC only started running five nanometre wafers for Bitmain in the third quarter of 2021, and the S19j Pro was on sale from the beginning of that year. The numbers do not line up either. The S19j Pro is rated at 29.5 J/TH, exactly what the seven nanometre S19 Pro does. The gain there came from 378 chips instead of 342 at a lower frequency, not from a new process.

BM1373 is not confirmed 3 nm

Chip sellers for the S23 series write "3 nm" with confidence. Yet neither Forbes nor the trade press that covered the S23 launch said anything at all about the die: only 9.5 J/TH for the hydro version and delivery dates. There is no confirmation from Bitmain. We do not use that figure and we suggest you do not either.

Four more common errors

• "The S5 has a BM1385." No, it has BM1384. BM1385 was announced eight months after the S5 shipped.
• "The S11 is 7 nm." No, it runs BM1387BF, sixteen nanometres, just a low voltage revision. The confusion started because the S11 and S15 arrived at almost the same time.
• "The S9j has a BM1393." No, BM1393 means the S9k and S9 SE only. The S9j runs BM1387BE or BM1387BF.
• "The S19k Pro is its own generation." No, it runs BM1366, the same chip as the S19 XP, in the BS and BP variants.

For the S21 and everything after it the honest answer is boring: the node is unknown. Vendors write "improved 5 nm", one shop writes 7 nm, Bitmain says nothing. We leave the number out of our own descriptions for those generations.

07Suffixes: why BM1368AA is not BM1368PA

One or two letters follow the number. That is not a serial and not a batch code, these are effectively different parts: different binning, different operating voltage, sometimes a different pinout. BM1387 has five such variants, BM1397 at least four, BM1370 six.

Within one number the variants are not interchangeable. Put a BM1397AD where an AG belongs and the best case is an unstable chain, the worst is a board that will not bring up voltage. The only reliable check is to read the silkscreen on a neighbouring working chip of the same board.

08What this changes when you buy or repair

The generation of the chip is the fastest way to see how much life a machine has left. Anything built on BM1387 only survives today where electricity costs almost nothing. BM1398 and BM1362, meaning the whole S19 series, are the backbone of the used market: 27.5 to 34 J/TH, which still earns money on a cheap tariff and stops earning on an expensive one. BM1366 and newer is what makes sense to buy for the long run.

In repair the marking decides the economics. Individual chips are sold one at a time, including the recent BM1370 and BM1373, and replacing a handful is almost always cheaper than a new hash board. It stops paying off once more than two domains in a row are knocked out, or once the board has been overheated: at that point a soldering station is not where the job ends.

Before you buy a used machine, check what firmware is on it. Factory images and checksums for 116 models sit on our Bitmain stock firmware page.

We keep hash boards, control boards, APW power supplies and consumables for the S19 and S21 series in stock in Valencia, and ship across Spain and the EU. If you are not sure which chip your machine has, send us a photo of the board and we will look at it together.

09Common questions

10Where to go next