In this section, we will discuss best practices for purchasing a used Bitmain Antminer S9, the machine on which this radiator retrofitting tutorial will be based. This guide also applies to other models of ASICs, as it is a general buying guide for used mining hardware.

The Antminer S9 is a device offered by Bitmain since May 2016. It consumes 1400W of electricity and produces 13.5 TH/s. Although it is considered outdated, it remains an excellent option for starting a mining operation. Since it has been produced in large quantities, spare parts are readily available in many regions of the world. It can generally be acquired peer-to-peer on sites such as eBay or LeBonCoin, as professional resellers no longer offer it due to its lower competitiveness compared to newer machines. It is less efficient than ASICs like the Antminer S19, which has been offered since March 2020, but this makes it an affordable used piece of hardware and more suitable for the modifications we will make.

The Antminer S9 comes in several variations (i, j) that make minor modifications to the first-generation hardware. We do not believe that this should influence your purchasing decision, and this guide works for all these variations.

The price of ASICs varies depending on several factors, including the price of bitcoin, network difficulty, machine efficiency, and electricity costs. Therefore, it is difficult to give an accurate estimate for the purchase of a used machine. In February 2023, the expected price in France generally ranges from €100 to €200, but these prices are subject to rapid change.

The Antminer S9 is composed of the following parts:

When purchasing a used machine, it is essential to verify that all necessary parts are included and in good working condition. During the exchange, you should ask the seller to turn on the machine to check its proper functioning. It is important to verify that the device turns on correctly, and then check the internet connectivity by plugging in an Ethernet cable and accessing the Bitmain login interface via a web browser on the same local network. You can find this IP address by connecting to your internet router interface and looking for connected devices. This address should have the following format: 192.168.x.x

Also, check that the default credentials work (username: root, password: root). If the default credentials do not work, you will need to reset the machine.

Once connected, you should be able to see the status of each hashboard on the dashboard. If the miner is connected to a pool, you should see all the hashboards functioning. It is essential to note that miners generate a significant amount of noise, which is a normal occurrence. Also, ensure the fans are functioning properly.

You can then remove the previous owner's mining pool to set up your own later. If you wish, you can also inspect the hashboards by disassembling the machine. However, this step is more complex and requires more time and some tools. If you wish to proceed with this disassembly, refer to the next section of this tutorial, which details the steps involved. It is essential to note that miners generate a significant amount of dust and require regular maintenance. You can observe this dust accumulation and the quality of maintenance by disassembling the machine. After reviewing all these points, you can buy your machine with a high degree of confidence. If in doubt, consult the community.

To summarize this guide in one sentence: "Don't trust, verify."