NerdOCTAXE - “El Ocho” the Iberian beast

It's probably worth writing a separate article about the entire NerdOCTAXE series, because there are so many cool and exciting details about its development - and that's exactly what I'm going to do. In the previous test article, a NerdOCTAXE revision 2.2 was tested. Although these are technically related, they are not the same- and that is exactly what we will be able to see very clearly in this test.

Today we're focusing on the open hardware beast “El Ocho”: 8 × BM1370 ASICs, which deliver 11.4 TH/s as standard. Some also advertise it with 12 TH/s, but let's be honest: this 12 TH/s is only achieved by clocking the ASICs higher. The standard clock speed of the NerdOCTAXE is specified at 700 MHz at 1210 mV and is also stored in the firmware, the legendary Nerd*OS.

But who is BitMaker? BitMaker is a pretty smart and laid-back guy from sunny Spain. He runs the Bitronics shop, which has lots of really cool stuff. He was one of the first to come up with the idea of not just using a Bitaxe, but actually improving it. He equipped it with the equally cool and well-known Lilygo T-Display S3 and completely ported the AxeOS firmware. And this display is not “just” a display: it also comes with an ESP module, on which many of the current open hardware miners are based. This idea was as simple as it was ingenious – and it made a whole range of different Nerd* projects possible in the first place.

The LILYGO T-Display-S3 is thus both “the brain” of the miner and the visual display – eye-catching, informative and, compared to many non-nerd projects, simply in a league of its own. And this is precisely where the magic lies: the ESP module, i.e. the “brain,” could be reused. This led to projects such as the legendary NerdQaxe+ with 4× BM1368 and later the NerdQaxe++ with 4× BM1370, launched by Pmaxsd. This development in turn led to the NerdOCTAXE with a total of 8× BM1370, invented and developed by Puall91. The basic concept of BitMaker was so good that it was also taken up by other projects, for example by the absolute OC king among 4-ASIC open hardware miners, the NerdQX.

Revision 3.1 is essentially based on Revision 2.2, but a version jump was necessary because several crucial technical changes were implemented. First, the power regulator was changed to TPS53667. However, the second change is even more important: two additional phases.

This gives Revision 3.1 a total of six VRM phases, which can distribute the overall load much more efficiently and, above all, more evenly. Revision 2.2, on the other hand, manages with four phases, i.e., two fewer. And this is precisely the crux of the matter: with high overclocking, each individual phase would be subjected to significantly higher loads, which would quickly lead to thermal and electrical pain thresholds. Of course, you can also push a Rev. 2.2 OCTAXE to its limits – I myself have overclocked it to 13 TH/s – but this is only possible with some discomfort and is certainly not a sensible continuous load.

Typically, the power consumption of the NerdOCTAXE Revision 3.1 – hereinafter referred to as “El Ocho” – ranges from 150 to 200 watts, depending on the frequency setting. As is well known in the nerd world, however, consumption can also be significantly reduced if the critical areas are properly cooled – more on that later.

In the course of these improvements, the PCB was also slightly revised in order to consistently achieve the goal: a multi-ASIC home miner based on open hardware with maximum stability. And yes, this has really been more than successful here.

The bottom line is that you can only get an original “El Ocho” from Bitronics, even though more and more derivatives and variations are now appearing on the market.

Bitronics has really put a lot of effort into the packaging – it looks more like that of a new graphics card than a home miner in this performance class. Included is a power supply (12 V / 20 A / 240 W), which is basically sufficient for operation at standard frequency.

The NerdOCTAXE was tested in its original state, i.e., without optimizations, modifications, or “quality of life” adjustments. I deliberately wanted to record the raw values of the overall package to ensure clean comparability with other reviews.

As with Revision 2.2, Revision 3.1 also relies on eight BM1370 ASICs. However, the key difference lies in the power supply. Compared to Rev. 2.2, Rev. 3.1 operates with six voltage regulator phases. This ensures better load distribution and has a positive effect on temperatures, stability, and overclocking potential.

The standard frequency is 700 MHz. In practice, this corresponds to ~11.3 TH/s at around 190–200 W (according to the UI). Cooling and control: Two Thermalright AXP36 with PWM fan control keep “El Ocho” well within limits during standard operation. However, with slight overclocking, I would plan to upgrade to a better cooler, because it is currently winter and the temperatures quickly appear “better than they are.” The next summer is guaranteed to come.

The topic of power supplies has accompanied me for years through many tests, findings, and articles. The included 12 V/20 A/240 W power supply is sufficient for standard clock speeds, but it does get noticeably warm. If you want to achieve the advertised 12 TH/s (or more) cleanly and consistently, I would definitely recommend using a Mean Well power supply.

The voltage is also on the low side at around 11.8 V. This is still within acceptable limits, but it may be an additional reason why the miner draws more power than necessary. At 12.3–12.5 V, the whole thing usually feels much more relaxed. And yes, power supplies have been the “soft spot” for many sellers/manufacturers for years – in my opinion, they are often not optimally chosen.

PCB/construction: “El Ocho” is manufactured with 2/2 oz copper. This improves heat distribution and thus indirectly supports cooling performance and overclocking capability. You can tell that improvements have been made in many areas.

What I personally still find lacking, however, are separate heat sinks directly on the VREGs. For me, this is actually a must for all Nerd* miners with 4 or more ASICs. Especially since a very good cooler is already mounted on the back – VRM heat sinks on the front would create a really nice synergy.

“El Ocho” (Revision 3.1) has slightly different default parameters than Revision 2.2. For the default frequency of 700 MHz, 1,210 mV is stored here. Due to numerous improvements, the firmware also officially supports 800 MHz. In practice, however, the voltage usually has to be adjusted manually in this range. It is important to monitor closely for any hashrate drops or instability. It is also pleasing to note that a maximum of 850 MHz can even be set via the Danger Zone of Nerd*OS.

As with other Nerd* projects, I tested the device with several typical profiles: ECO mode at 495 MHz, standard at 700 MHz, and maximum at 800 MHz, without Danger Mode. In the end, I ended up with four settings, as I naturally wanted to know how “El Ocho” performs at 600 MHz – as a direct comparison to Revision 2.2.

As I mentioned above, the useful voltage ranges for “El Ocho” are slightly different from those for the NerdOCTAXE in Revision 2.2, which is why, when operating outside the standard frequency, a little testing is necessary to find the optimal voltage for a stable hashrate. Despite all the improvements, the silicon lottery remains – and that is precisely what makes this step necessary, unfortunately. On the other hand, if everything were perfect, we would have much less to measure and optimize.

What particularly surprised me was that the values displayed in the UI are extremely close to the measurements I took with a Shelly smart meter at the power outlet. I have hardly ever seen such a small deviation in a home miner – it's almost unusually good. However, there seems to be a slight inaccuracy in ECO mode. In this mode, the UI reports higher consumption than the smart meter actually measures. Therefore, my recommendation remains: always measure consumption directly at the power outlet, because that is ultimately the most reliable reference.

At 800 MHz, however, the supplied power supply is at 100% of its limit, which can quickly lead to a defect. It also gets extremely hot, which is never a good sign if you take the 80% rule seriously. Note: A power supply should never be operated continuously at more than 80% of its rated power. At 240 W, this means a maximum total load of approximately 192 W (measured at the outlet), which should be continuously demanded from the power supply. The limit is also directly visible in the voltage: it drops from 11.8 V to 11.6 V, and 11.5 V is usually the first real undervoltage warning zone. This is not particularly healthy for either stability or the hardware.

I was very pleasantly surprised by the overall low VREG temperature, even though there are no separate heat sinks on the VREGs and no direct airflow is directed over this area. I hadn't expected that. Especially since the NerdOCTAXE in revision 2.2 was still a real work in progress at this point. I have often recommended staying in the 495 MHz range and definitely using heat sinks to help.

So here you can see: The concept works much better, but at the same time there is still clear room for further optimization. A few small heat sinks would further lower the temperatures, improve efficiency, and potentially even reduce power consumption. And these small coolers are really not expensive.

In my opinion, you should still seriously consider purchasing a MeanWell LRS-350-12. For the simple reason that this power supply allows you to regulate the voltage cleanly – and if you ever decide to overclock, you'll have a sufficiently dimensioned PSU that doesn't scrape along the limit.

The same applies to cooling: depending on your setup, a Thermalright x47 or x53 full copper cooler would definitely be the more recommendable choice here. There is currently no update for the well-known NQ-HELIX Shroud, which allows you to mount a 120mm fan directly on the coolers, but that's only a matter of time: an update from PlebBase will follow soon – in the usual manner, of course, including detailed tests.

As I said, the x36 coolers are adequate, no question. But personally, I find the fans a tad too loud. Of course, everyone's perception is different – some people don't care, others go crazy at the slightest high-frequency whirring. I tend to fall into the second category. I would much prefer Noctuas in combination with an NQ-HELIX. But that's not a “flaw” of the Bitronics setup, nor is it something that NerdOCTAXE is somehow to blame for – it's simply the nature of “out of the box” vs. “custom tuning.” And honestly, it would be boring if there was nothing left to optimize. :)

However, what I would really recommend to everyone is to stick heat sinks on the VREGs. This not only extends the service life of the NerdOCTAXE, but also ensures significantly quieter operation in practice – because less thermal stress usually means less “counter-regulation.” And yes: this will also noticeably reduce power consumption.

It really is a very successful overall package, apart from a few minor criticisms that could be remedied or significantly improved through Pleb optimizations. The NerdOCTAXE revision 3.1, “El Ocho”, with improved copper conductor tracks is absolutely rock solid, and this improvement alone means that nothing stands in the way of overclocking. 

From a technical point of view, it is an absolutely successful mega-adaptation that you definitely don't want to miss out on. So much hash rate in such a small space, with high efficiency... 

Currently, there is really nothing more powerful in the open hardware BTC mining segment, so it's an absolute must for every pleb.

When overclocking, you should of course ensure significantly improved cooling and sufficient power supply, but that's nothing new.