ASIC Firmware Guide — Braiins OS+, LuxOS & VNish Compared for Home Miners
Required for Loki Kit and LuxOS PSU Bypass 120V Mining
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Why Aftermarket Firmware?
Stock Bitmain firmware doesn't allow you to underclock miners enough to run on 120V power. Aftermarket firmware unlocks this ability, letting you:
- Lower frequency/voltage to reduce power draw
- Run industrial ASICs on standard 120V/15A outlets
- Fine-tune performance vs power consumption
- Often improve efficiency (J/TH)
Before flashing anything, run your miner through the calculator to see what your power draw and profit look like at your current electric rate — then compare after tuning.
Need a miner to flash? Shop on eBay: Antminer S19 ↗ · Antminer S19j Pro ↗ · Antminer KS5 ↗
⚠️ Aftermarket firmware may void your warranty. Always research compatibility with your specific miner model and control board before flashing.
Popular Options
Developed by Luxor Technology. Popular choice for Loki rigs and "Urlacher" builds. Mining on Luxor Pool waives its 2.5% pool fee; the 2.8% dev fee still applies.
- Excellent underclocking support
- Clean web interface
- Actively maintained
- Good for S19K Pro and S21
- PSU Bypass for 120V custom builds (added Feb 2026)
Russian-developed firmware with powerful auto-tuning features. Popular in the home mining community for its efficiency gains.
- Automatic chip tuning
- Immersion cooling support
- Works with most S19 variants
- Fixed frequency mode for Loki
From the creators of Slush Pool (now Braiins Pool). Open-source base with premium features in OS+ version.
- Excellent auto-tuning
- Power target mode (set watts, auto-adjust hashrate)
- 0% pool fee if mining on Braiins Pool (the dev fee still applies)
- Strong community support
Quick Comparison
| Firmware | Dev Fee | Best For | Pool Fee Waived On |
|---|---|---|---|
| LuxOS | 2.8% | Loki/Urlacher & PSU Bypass builds | Luxor Pool |
| VNish | 2.8% | Auto-tuning, efficiency | No |
| Braiins OS+ | 2–2.5% | Power target mode | Braiins Pool |
Shutdown, Restart & Scheduling
If you mine on solar or time-of-use electricity rates, you need to stop and start miners on a schedule. How that works depends entirely on your firmware. Some make it easy. Others will brick your remote access if you use the wrong command.
Shutdown Behavior by Firmware
| Firmware | Stop Mining | Full Shutdown | Remote Restart | Scheduling |
|---|---|---|---|---|
| Stock (Bitmain) | Web UI only | No SSH (locked since 2019) | PDU power cycle only | Not supported |
| Braiins OS+ | bosminer stop | poweroff (loses network) | PDU power cycle; bosminer start after stop | Cron jobs |
| LuxOS | API or web UI | poweroff (miner stuck OFF) | PDU power cycle only | Limited |
| Vnish | Web UI toggle | poweroff (loses network) | PDU power cycle after poweroff | Built-in |
⚠ The Poweroff Trap: Running poweroff or shutdown over SSH kills the miner's network stack. The miner is now off and unreachable — nothing over the network can turn it back on. You must physically power cycle it or use a smart PDU. This applies to ALL firmware.
Stock Firmware — SSH Is Locked
Bitmain locked SSH access on S19-series miners starting in 2019. If you're on stock firmware, you cannot use any SSH commands — no poweroff, no reboot, no cron scheduling. Your only remote option is the miner's web interface (for monitoring) and a smart PDU (for power cycling). This is the #1 reason home miners switch to aftermarket firmware.
Braiins OS+ — The Most Flexible
bosminer stop pauses mining without shutting down the miner — your SSH session stays alive and the miner stays on the network. bosminer start resumes mining. This is the safest software method for solar schedules. Cron jobs work reliably for automated stop/start. Known issue: pool settings may reset after a full restart — verify your pool config after any reboot.
LuxOS — Use PDU, Not SSH
LuxOS supports remote management through its API and web UI, but poweroff over SSH leaves the miner completely stuck off with no remote recovery path. If you're on LuxOS and need to shut down on a schedule, use a smart PDU to cut and restore power rather than any SSH shutdown command. See our 240V Power Control guide for recommended hardware.
Two Ways to Run on 120V — Loki Board vs LuxOS PSU Bypass
An Antminer checks which power supply is connected. If it’s not a model it expects — like a 120V supply — it won’t run. For years the only fix was a Loki board. Since February 2026, LuxOS has a firmware setting that does the same job.
| Loki Board | LuxOS PSU Bypass | |
|---|---|---|
| What it is | Small hardware board | Setting inside LuxOS firmware |
| Extra cost | Board purchase | None beyond LuxOS (2.8% dev fee; Luxor Pool waives its pool fee) |
| Install | Wiring / control board changes | Turn on in LuxOS, then reboot |
| Firmware | LuxOS, VNish, or Braiins OS (depends on kit version) | LuxOS only |
| 120V power supply needed | Yes (e.g. Bitmain APW3++) | Yes (e.g. Bitmain APW3++) |
| Reversible | Remove the board | Turn the setting off |
Luxor’s changelog for February 11, 2026 lists: “Added option to bypass the PSU for custom builds.” It is set with the psuset command (bypass_enabled) and only takes effect after a reboot. See Luxor changelog and psuset docs.
⚠️ Check your control board first. Luxor’s docs do not list which models support PSU Bypass. Third-party guides report it works on S19 and S21 series with Amlogic control boards and does not currently work on CVITEK (CV1835) boards. Either path still runs the miner at reduced power on a dedicated 120V/20A circuit — see the Electrical Setup guide. Bypassing the PSU check does not bypass electrical limits.
For Loki Kit Users
If you're running a Loki Kit setup on 120V, you'll need firmware that supports:
- Fixed frequency mode - Set a specific frequency to keep power under 1200W
- Power limit - Some firmware lets you set a wattage cap
- Hash board spoofing - The Loki Kit tricks the miner into thinking all boards are present
Most Loki builds use LuxOS or VNish. Start at the lowest frequency setting, then slowly increase until you hit ~1200W at the wall.
Where to Get a Loki Kit
The Loki Kit is made by Pivotal Pleb Tech and sold through several retailers:
- Pivotal Pleb Tech (original creator)
- Altair Technology
- Nakamoto Mining
- D-Central Technologies (pre-built Loki rigs)