Bitmain Antminer KS3 (9.4Th)

The Bitmain Antminer KS3 (9.4 Th) is a dedicated Kaspa (kHeavyHash) ASIC miner released in September 2023. It produces a nameplate 9.4 TH/s on the kHeavyHash algorithm, draws roughly 3,188–3,500 W at the wall, and runs on a locked CVitek control board. It is a 2023-generation Kaspa machine, now sitting below the latest KS5-class hardware.

Chip and hashboard architecture

Unlike Bitmain’s SHA-256 flagships, the KS3 is not a Bitcoin miner. It runs kHeavyHash, the proof-of-work used by the Kaspa (KAS) network, and is built around Bitmain’s purpose-built kHeavyHash ASIC rather than the BM1397/BM1398/BM1368 silicon family used in the S-series. Bitmain has never published a public die-level datasheet for its Kaspa ASIC, so D-Central treats per-chip core counts and process node as unconfirmed rather than repeating marketing numbers that cannot be verified.

What is well established is the chassis. The KS3 follows the standard Antminer mechanical layout: multiple hash boards driven over an 18-pin ribbon cable from a single control board, with the ASICs daisy-chained in series and grouped into voltage domains. This is a critical point for anyone planning to service one: like every Antminer, the KS3 controls voltage per domain (a group of chips sharing a regulated rail), never per individual chip. A single weak or shorted die pulls down its whole domain, which is why board-level diagnosis always works in domain blocks rather than chip-by-chip guesswork.

The control board is the most distinctive part of the KS3 and the part that most affects what you can do with the machine. The KS3 ships on a CVitek (CVITEK / SOPHGO) CV1835-family control board — the same SoC platform Bitmain uses on the S19k Pro, S19 XP, S21, T21, KS5 and X5. CVITEK originally designed the CV1835 as a smart-vision / edge-AI processor (IP cameras, face recognition) before Bitmain repurposed it for mining control. On the KS3 it appears in the C88 / CB8 board family and is identifiable by a single 4-pin fan header and the word « CVITEK » silkscreened on the main SoC. There is no FPGA and no micro-USB OTG port; the board talks to the hash boards over a software UART and exposes an external SD-card slot next to the Ethernet jack.

Real-world power and efficiency

Bitmain rates the KS3 at about 9.4 TH/s for roughly 3,188 W at the wall under datasheet conditions (~0.34 J/GH, or about 339 J/TH). In the field, wall draw routinely runs higher — the conservative ~3,500 W / 372 J/TH figure on our spec card reflects what these units actually pull once PSU efficiency, ambient temperature, and 208 V vs 240 V input are accounted for. Both numbers are « right »; they just describe different points between the datasheet bench and a hot mining room.

One number that is easy to misread is J/TH. kHeavyHash terahashes are not comparable to SHA-256 terahashes. A 372 J/TH reading on a Kaspa miner does not put the KS3 in the same « legacy » tier as a 372 J/TH Bitcoin miner — the algorithms, hash definitions, and economics are entirely different. The honest way to judge the KS3 is against other Kaspa ASICs, where it lands as a solid mid-generation unit that has since been out-paced by newer KS5-class machines on efficiency per KAS.

Tuning headroom on the KS3 is far more limited than on a SHA-256 Antminer, mostly because the firmware ecosystem around it is thin (more on that below). Where SHA-256 operators lean on autotuners and curated power profiles to dial efficiency, Kaspa operators are largely working with stock behaviour. If you do plan to undervolt or cap power, our ASIC power profiles database is the right starting point for understanding the voltage/frequency relationship before you change anything.

Firmware compatibility and the CVitek lock

This is where the KS3 differs most from a Bitcoin Antminer, and where most owners get surprised. The CVitek CV1835 control board uses an ARM Trusted Firmware FIP boot chain (BootROM → FSBL → OpenSBI/BL31 → U-Boot → Linux) protected by RSA-2048 secure boot and AES encryption with eFuse-burned keys. Once those one-time-programmable fuses are set and locked at the factory, only firmware signed with Bitmain’s private key can boot the bootloader chain.

The practical consequence: aftermarket firmware on a CVitek board does not persist across a reboot. Third-party firmware suites can be written into a secondary NAND partition and run while the miner is up, but the signed U-Boot resets the active boot flag back to the stock Bitmain partition on every cold boot. On power-cycle the machine returns to stock, and a network « re-injection » toolkit has to detect that and re-activate the custom image — every single time. Some firmware projects have reported persistent installs on specific CVitek sub-revisions, but it is the exception, not the rule, and several require a remote/assisted install for CVITEK boards. For most KS3 operators the realistic answer is: run stock, point it at your pool, and don’t count on the autotuning, profile, and monitoring features you’d expect from an aftermarket Bitcoin firmware. If aftermarket firmware is a hard requirement for your fleet, talk to us first — the CVitek lock is a hardware reality, not a setting you can flip.

Credit where it is due: this lockdown is good security engineering on Bitmain’s part. It makes the KS3 hard to repurpose, but it also makes stock firmware tamper-resistant, which matters in hosted environments.

Common faults and troubleshooting

Most KS3 problems are the same failure modes that affect any high-power Antminer, just on a Kaspa hash board:

• Dead or partial hash board — a chain reports zero or a reduced ASIC count. Because chips are wired in series within voltage domains, one open or shorted die can silence an entire chain. This is a board-level diagnosis, not a reset-and-hope fix.
• Over-temperature shutdowns — at ~3.5 kW the KS3 makes serious heat. Blocked intakes, failed fans, dried thermal paste, or a hot ambient (it is effectively an 11,942 BTU/h heater) will trip thermal protection. Clean filters and verify both fan tachometers first.
• PSU and power instability — brown-outs, weak breakers, or a degrading PSU cause restarts and hashrate drops well before a board is actually at fault.
• Control-board / SD quirks — because the CVitek board reverts to stock on reboot, a machine that « lost its firmware » after a power cut is usually behaving exactly as designed, not failing.

For a guided walk-through of symptoms, error states, and the right next step, start with our ASIC fault finder, which routes common Antminer error conditions (chain offline, zero ASIC found, temperature-too-high) to the matching diagnostic page.

Repair and longevity

A 2023 Kaspa miner is well worth repairing rather than scrapping, especially while KAS remains worth mining. D-Central has run an in-house ASIC repair lab in Laval, Québec since 2016, and the KS3’s hash boards respond to the same component-level techniques we use across the Antminer line: domain-by-domain voltage tracing, reflow and chip replacement, regulator and boost-circuit repair, and PSU diagnosis. The locked CVitek control board cannot be « fixed » with a firmware reflash, but it rarely needs to be — the failures that take a KS3 offline are almost always on the hash boards, fans, or PSU, all of which are serviceable.

If your KS3 is down or under-hashing, our ASIC repair service covers diagnosis and board-level work, and we can advise on whether a given unit is economical to keep running.

Who the KS3 is for — and buying

The KS3 makes sense for one specific operator: someone who believes in Kaspa, has a home or small space that can absorb 3.5 kW of continuous heat, and wants exposure to KAS hashrate without chasing the absolute newest hardware. Its 11,942 BTU/h output is genuinely useful as supplemental heat — ducted into a workshop or basement in a cold Canadian winter, it turns money you’d spend on heating into coins. It is not the right pick if you want best-in-class efficiency per KAS today; that title has moved to KS5-class machines.

Because availability on older Kaspa hardware is variable, the KS3 is best treated as a build-to-order / refurbished-fleet purchase rather than something pulled off a shelf. Browse the full lineup and current specs in our ASIC miner database, and reach out if you want a hand matching a Kaspa unit to your power and heat budget.

Generational context

Bitmain did not invent the Kaspa ASIC — IceRiver pioneered the category with its KS0/KS1/KS2 units before the major SHA-256 manufacturers entered. When Bitmain shipped the Antminer KS3 in 2023 it pushed Kaspa hashrate density forward, and the network’s GHOSTDAG blockDAG — designed for very high block rates rather than Bitcoin’s ten-minute cadence — has only grown more competitive since. That competitiveness cuts both ways: the same momentum that made the KS3 attractive in 2023 has since produced more efficient KS5-class hardware, and network difficulty has climbed accordingly. The KS3 remains a capable, repairable, mid-generation Kaspa miner — best understood as a heat-positive way to hold KAS hashrate, judged honestly against its own algorithm rather than against Bitcoin ASIC efficiency charts.