After getting a Bitaxe in November 2024 I decided to watercool it as the air cooling was insufficient: although a Noctua NF-A4x10 PWM fan was used the temperatures on the BM1370 were at about 60° C and the hashrate was around 1.1 Th/s.
Ingredients
Following parts were utilized. Note that all of them were used in custom waterloops previously, and there is the possibility get them or similar products for a reasonable price:
- A generic Koolance GPU-210 waterblock. It comes with mounting screws and fits neatly on the Bitaxe.
- An Alphacool MCX one distributor. Usually it serves the purpose to distribute cooling liquid into tiny tubes, here it is simply used as connector.
- Already bended 12mm outer-diameter (OD) solid tubes
- Tube fittings EK-HDC 12mm G1/4
- A daisy-chainable Arctic P12 PWM PST fan.
- The waterpump-reservoir combo Alphacool Eisbaer Solo with a 3-pin power connector .
- A EK CoolStream SE-120 Radiator
Putting it together
Using hard tubes has the advantage that all parts stay in place without needing a stand. When properly aligned, neither the Bitaxe nor the radiator, nor the pump needs fixation. The pump and radiator were arranged such that they leave the waterblock floating. This way it was possible to attach the Gamma to the waterblock later on:
The waterblock came with distance mounting screws, and plastic washers were used to prevent damage to the PCB:
The mounting screws were attached to the Bitaxe such that it can be mounted to the floating waterblock on the already assembled cooling setup later on:
Cooling results
There are two PSUs in use: A 20 W PSU for the Bitaxe itself, and an adjustable power supply for the cooling setup. The latter serves the purpose to variate the power and figure out a sweet spot to get enough cooling while still staying quiet. It powers first the Arctic fan and then the Alphacool waterpump in a daisy-chained way:
Limiting the overall current in the adjustable power supply to 0.21 A keeps the voltage at around 7.19 V which is the lowest voltage the pump practically needs to function.
This leads to a low power consumption of approximately 1.5 W being enough to keep the fan and pump operational. The fan spins fast enough and the pump provides enough water flow to cool down the BM1370 chip to around 35 °C. The noise level directly next to the fan and pump is approx. 30 dB. Half a meter away it is silent with less than 20 dB.
The BM1370 runs with a frequency of 675 Mhz and a core voltage of 1.2 V in this setting, yielding a hashrate of 1.4 Th/s on average. Without counting in the cooling, the Bitaxe consumes 19.6 W of power.
Next steps
This is all preliminary and following improvements could be helpful:
- Use a PSU with more than 30W for the Bitaxe to ramp up the frequency on the BM1370.
- The voltage regulator is at a temperator of 70 °C degrees, hence, it would profit from cooling with small heatsinks.
- Add a heatsink on the backside of PCB at the BM1370 region for additional cooling.
- Attach the cooling setup to the same PSU as the Bitaxe, and thereby keep the voltage adjustable from 7 V and 12. This removes the need to use two power supplies.