What are the default Bitaxe frequency and voltage?
AxeOS, the firmware on every Bitaxe, ships with a default frequency and core voltage for each chip. These values come from the firmware source (ESP-Miner) and are what the miner uses after a fresh install:
| Model | Chip | Default frequency | Default core voltage | Expected hashrate at default | Preset range in AxeOS |
|---|---|---|---|---|---|
| Bitaxe Gamma | BM1370 | 525 MHz | 1150 mV | 1.07 TH/s | 400 to 690 MHz, 1000 to 1250 mV |
| Bitaxe Supra | BM1368 | 490 MHz | 1166 mV | 625 GH/s | 400 to 575 MHz, 1100 to 1300 mV |
| Bitaxe Ultra | BM1366 | 485 MHz | 1200 mV | 434 GH/s | 400 to 575 MHz, 1100 to 1300 mV |
The Bitaxe Gamma Turbo has two BM1370 chips, so its expected hashrate at the same frequency is twice a Gamma's. Some makers ship their boards with their own tuned defaults; if your unit came pre-set, those values are a sensible baseline.
How does AxeOS calculate expected hashrate?
AxeOS multiplies the frequency in MHz by the chip's number of small cores and the number of chips. For a Gamma's BM1370, with 2,040 small cores:
| Frequency | Expected hashrate (Gamma) | Change from default |
|---|---|---|
| 490 MHz | 1000 GH/s | -7% |
| 525 MHz | 1.07 TH/s | default |
| 550 MHz | 1.12 TH/s | +5% |
| 600 MHz | 1.22 TH/s | +14% |
| 625 MHz | 1.27 TH/s | +19% |
| 690 MHz | 1.41 TH/s | +31% |
Expected hashrate is the best case. If the measured hashrate stays well below it, the chip is producing errors at that frequency and voltage, and the setting is not stable.
What temperatures are safe for a Bitaxe?
- Chip (ASIC) temperature: AxeOS treats 75 °C as overheating. Community guides recommend keeping it under about 65 °C for long-term running.
- Voltage regulator (VR) temperature: AxeOS's limit is 105 °C. Aim to keep it under about 80 °C.
When either limit is passed, AxeOS stops mining, sets the fan to 100%, waits for the chip to cool, then restarts with the core voltage lowered by 100 mV and the frequency lowered by 100 MHz, and saves those lower values. If your settings have mysteriously dropped, an overheat is the likely cause.
How do you change frequency and voltage safely?
- Start from default and let the miner run for at least 30 minutes. Note hashrate, chip temperature, VR temperature and power.
- Change one thing, one step at a time. In AxeOS Settings, raise the frequency one preset step, for example 525 to 550 MHz on a Gamma. Save and restart.
- Watch for 30 minutes. If measured hashrate tracks the new expected figure and temperatures stay in the safe range, the step is stable.
- If hashrate falls short, try one voltage step up. More voltage helps stability but adds heat and power fast.
- Stop at the first sign of trouble: rising errors, hashrate far below expected, chip above 65 °C or VR above 80 °C. Go back one step.
Careful: overclocking is at your own risk and can shorten the life of the chip and voltage regulator. Higher settings also draw more current, so the 5 V supply must handle it: a Gamma needs a quality 5 V supply of about 6 A even at stock.
Is overclocking a Bitaxe worth it?
Usually only a little. Power use rises faster than hashrate, because it grows with frequency and roughly with the square of voltage. A higher setting therefore costs more electricity for every extra terahash, and makes more heat and fan noise. For a 1.2 TH/s miner, a 10% overclock adds about 0.1 TH/s, which barely changes either its earnings or its solo odds. See Can a Bitaxe find a block? for the numbers.
Many owners go the other way and run slightly below default frequency and voltage. The miner then runs cooler and quieter and uses less power per terahash, at the cost of a little hashrate. On expensive electricity this can be the better choice; Is home mining profitable? explains why.
Which changes help most, in order?
- Good airflow. Free space around the fan and heatsink, away from walls and other hot devices. Lowers every temperature at no cost.
- A proper power supply. Brownouts cause reboots and errors that look like bad settings.
- A better heatsink or fan if you want to push frequency, from the board's maker.
- One frequency step up, only after the steps above.
- Voltage increases last, in single steps.
Do the Supra and Ultra tune differently?
The method is the same, but the older chips have less headroom. The Supra's BM1368 and the Ultra's BM1366 run at higher default voltages than the Gamma's BM1370 and produce fewer terahashes per watt, so each step up adds relatively more heat. Their preset ranges in AxeOS stop at 575 MHz. On these models, running at default or slightly below is often the better trade, especially in a warm room. If you want more hashrate from one device, a newer chip gives more than any overclock: a Gamma at stock beats an overclocked Ultra.
What fan setting should you use?
AxeOS offers automatic fan control, which raises the fan speed as the chip warms. That is the right choice for most people. A fixed fan speed can be quieter, but then you are responsible for watching temperatures, especially in summer. If the fan already runs near full speed at stock settings, do not overclock; improve airflow first.
Do settings affect mining on DirectPool?
No pool settings need to change. DirectPool credits work by share difficulty, so a faster Bitaxe simply submits more work and earns a proportionally larger part of each block the pool finds. Stable settings matter more than high settings: rejected shares and reboots lose work. Pool fields are covered in the Bitaxe setup guide, and your live share of the next block is on the verify page. For overclocking experience from the community, bitaxe.de publishes an overclocking guide.