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Bitcoin Mining Insights

Why Custom Mining Firmware Matters

Why should miners consider installing custom firmware? This article explores the risks and benefits of not sticking with the ASIC manufacturer’s stock firmware.

Published on Jun 27, 2022
Published on Jun 27, 2022

Table of Contents

Braiins believes miners should have more transparency and choice about what firmware runs on their mining hardware. Ultimate operator freedom and choice for miners comes from being fully sovereign over all aspects of their hardware, including the installed firmware. This article is an introduction for new miners to understand why custom mining firmware matters and how it improves the operations of a mining farm. 

Customized Hardware Trends

Beyond mining firmware, increasing awareness and acceptance of customizable firmware and software for day-to-day hardware devices is becoming a noticeable trend. Growing numbers of less sophisticated technology consumers are taking simple steps to better control how their devices run. For example, consumers buy a Google Pixel phone and flash it with a customized operating system (i.e., CalyxOS or GrapheneOS). Bitcoin investors also have the ability to choose from a bevy of key storage software products and customize their full node to run however they prefer. 

Miners should have the same flexibility to control what firmware runs on their machines and how they can optimize the performance of those miners. 

A World Without Custom Firmware

So, consider a miner who bought one latest-generation mining machine. It’s theirs to operate, but running, optimizing and controlling the machine however they choose—like someone might want to do with their mobile phone—is a far cry from reality. In most cases, before custom firmware, miners were forced to buy hardware, receive it whenever the manufacturer ships, and run whatever firmware the manufacturer installed, trusting that the firmware is reliable and not at all malicious or buggy. 

But this trust in manufacturer-installed firmware has been broken before, emphasizing the need for miners to have a choice in what firmware runs on their mining hardware. 

Example 1: Antbleed

In 2017, Antminer’s manufacturer, Bitmain, developed a backdoor to their stock firmware called “Antbleed”. This backdoor was added to all Antminer machines at the time, and it allowed manufacturers to remotely access Bitmain machines. With Antbleed, Bitmain could power down a machine, redirect its hashrate, and control the hardware however they chose. Bitmain maintains their position that this “feature” was intended as a machine management and performance diagnostic tool, but miners quickly became concerned with the access this backdoor gave to Bitmain and learned about the dangers of closed-source, manufacturer-installed firmware.

Example 2: ASIC Boost

Another incident involving Bitmain firmware involves a feature added to improve efficiency of mining chips. But this feature, called AsicBoost, was kept a secret known only to the manufacturers, and after hardware was shipped to Bitmain customers, the AsicBoost option was no longer available. In this way, Bitmain secured an important edge in machine performance over the rest of the network. If the firmware was fully open-sourced and publicly available, this boost feature would have been available to the entire market. 

The AsicBoost feature idea came from two researchers: Timo Hanke and Sergio Lerner. They discovered how to tweak the mining ASICs to achieve a 10% to 20% increase in efficiency with energy savings or elevated hashing. 

These secret improvements, diagnostic features, or backdoors were possible at that time because the firmware market had no real competition. Manufacturers could develop and install whatever they chose. Fortunately, none of these incidents had long-lasting effects on the Bitcoin network. But they underscore the importance of open-source mining firmware and competition in the firmware market to prevent vulnerable or malicious firmware products and mitigate risks from blindly running a manufacturer’s firmware. 

Braiins OS+ Development and Historical Review

Dragonmint machines were the first type of mining hardware that Braiins developed custom firmware for, but Bitmain machines quickly became the priority for future versions of the Braiins OS+ firmware due to customer demand. As firmware for Bitmain Antminers were developed and released, support for the S9 machine was (and still is) the most popular version of Braiins OS+. 

Today, it is even still possible to download cgminer source code and use it as a base for the Braiins fully open-source firmware. But mining machine manufacturers soon realized they could stop publishing the source code for newer generations of their machines, even for parts that are under the General Public License (GPL), Since then, for Antminer S11, S15, S17, and other models, the manufacturers have not published source code for the factory-installed firmware, which, of course, makes development for custom firmware more difficult – but far from impossible. 

As another example of custom firmware development challenges, the Antminer S19 model was built with a new feature called secure boot, which prevents standardized installation and running of custom firmware. For these and other challenges, though, the solutions are simply a matter of electricity, which means they exist, even if the solution’s development takes time.

Pros and Cons of Custom Firmware

Here’s a brief overview of some fundamental benefits and disadvantages of custom firmware products compared to using a manufacturer’s stock firmware. 


  • Energy efficiency optimization (up to 20% better J/TH)
  • Boost up and downvolt ASICs (play with temperatures, fan speed, etc.)
  • Over and under clock, and autotune
  • Many remote configuration options
  • Scale up hashrate with limited power supply
  • Pay 0% pool fees on Braiins Pool with Braiins OS+
  • Virus protection 
  • Extended machine lifespan


  • Risk of damage to hardware with uneducated use
  • Potential security risk from remote operation (be sure to follow all necessary security steps)
  • Manufacturer warranty limitations
  • Developer fee payment (Braiins OS+ isn't free)

Why Use Braiins OS+ Firmware?

Braiins is proud to have developed the Bitcoin mining industry’s leading custom, open-source firmware product and to have added proprietary autotuning algorithms to it which optimize ASIC performance. Besides being based on the original open source Braiins OS that was launched in 2018, using Braiins OS+ offers several key benefits to miners, including immersion cooling features, automatic firmware updates, on-screen displays, machine pre-heat options, and easy installation with a friendly user experience and bulk installation settings. 

With Braiins OS+, miners can build automatic systems to read and monitor real-time machine operation data through an API to track temperature alerts, energy consumption, fan activity after powering down, and more. Miners can also disable a machine’s fans using the firmware’s fan emulators to prepare the hardware for an immersing cooling system. 

All of these points of customization allow for noise reduction, lifespan extension, efficiency improvements, and increased revenue. 

Boosting Revenue with Custom Firmware

Instead of always buying the latest generation hardware, efficiency improvements and hashrate increases with custom firmware offers performance enhancements for older hardware. And maximizing the utility of hardware a miner already owns makes perfect sense. 

Here is where machine autotuning and over (or under) clocking are relevant. Overclocking and autotuning adjust the hashing frequencies of a machine’s hashboards, which alters the hardware’s performance. But the key difference between overclocking and autotuning is the intelligence and sophistication of these hashing frequency adjustments. 

For example, miners who overclocker are willing to make their machines slightly less efficient (i.e. operate at a higher rate of Joules per terahash) in order to stack more sats. Autotuning optimizes the performance of every chip on a machine’s hashboards by calibrating the frequencies and voltages, raising the total efficiency by up to 25% and helping miners stack more sats per Watt of energy they consume. 

Final thought: installing custom mining firmware is a learning experience that really isn’t too difficult and can dramatically improve a miner’s operational efficiency and total revenue.

You can view the changelog also in our documentation.
See the full changelog
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About Braiins

Bitcoin mining software company: Braiins Pool, Braiins OS+ & Stratum V2.

By miners, for miners.

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