Today on the net you can often find cases on mining BTC and altcoins with stories about the profitable use of used ASIC miners. With the growth of the exchange rate, interest in mining is returning, and the crypto winter has left a huge number of used devices on the secondary market. For example, in China, where the cost of electricity did not allow counting on even the minimum yield of crypto emission at the beginning of the year, thousands of inexpensive devices appeared on the secondary market.
These ASIC miners were bought in bulk by cunning intermediaries and today are offered in huge numbers both in the domestic market of China and beyond. An impressive amount was purchased by Chinese miners back in the spring. A lot of used ASICs regularly leave for Russia.
Some crypto entrepreneurs believe that with equal performance, a used ASIC, due to its low cost, pays off faster. In a number of specific cases, this is indeed the case. At the same time, there are reports of problems with cooling, sudden failure and a decrease in hashrate. Under the cut about the benefits and risks of using used mining equipment.
The post does not contain information about the profitability and profitability of mining, the effectiveness of the use of certain devices for the production of cryptocurrencies. Any mentions of manufacturers, operators, pools and media are not related to advertising and are used to specify the source of information. The information in the article is collected on the basis of personal experience, the experience of entrepreneurs and companies providing industrial mining services, as well as discussions on cryptocurrency forums. Due to the volatility and dependence of the cryptocurrency exchange rate on the market, nothing today guarantees the profitability of investments in mining.
Warranty issue and possible risks
It is known that the guarantee for miners (for example, for the popular Antminer S9 from Bitmain) almost never exceeds 3 months. As a rule, a used ASIC has been used for a longer time and is almost guaranteed in non-stop mode. You don't have to be a technical expert to understand that these modes of operation do not make the device more reliable. If such problems occur with a new device, users are protected by a warranty. When buying used equipment, it is quite possible that you will have to shamanize with a soldering station.
The guarantee is not something universal, especially when the intensity of exploitation of the miners is high and the conditions leave much to be desired. In any case, this is a temporary protection against possible problems in the early stages of using the ASIC.
The old truth is that most problems with complex electronic equipment occur at the beginning and end of their life. The early ones are more often associated with manufacturing defects - the guarantee protects them from them, the cause of the later ones, as a rule, is natural wear and tear.
It is also known that cooling problems, and, accordingly, a serious risk for chips in new miners occur 4 times less often than in used ones. At the same time, a new ASIC can be returned under warranty, a used one will require investments in repairs.
How ASIC miners die
In order to imagine in detail what can happen to the miner, I propose to consider the chain of events that leads the device to failures and breakdowns.
As already noted, first of all, the issue of reliability seriously affects the mechanical elements, i.e. cooling. This is especially facilitated by the use in dusty rooms, regular vibration of farms with devices placed on them, the use of cheap fans with a low resource and unstable characteristics in the design.
Dust clogged into technological holes, as well as low-quality filters, reduce the efficiency of cooling, increase friction during fan operation, and increase the risk of device fire at critically high temperatures on the board elements. When the temperature of the chips rises to a critical temperature (115 degrees Celsius), the printed circuit board can delaminate, which leads to a complete failure of the hashboard.
It is also important to note that ASIC manufacturers often provide them with higher quality chips immediately after the release. When a device becomes popular, the quality of the chips goes down. So on the forum Users difference in chips for the popular Antminer S9 miners, which, according to users, were equipped with more reliable chips until November 2017.
Technical specialists of BitCluster, a large Russian hosting company who monitor equipment in the company's mining hotels, distinguish 2 types of chip degradation as a result of temperature and vibration - burnout (mainly thermal damage to the chip in the form of melting the case) and dump (mainly mechanical damage to the chip in the form of destruction of the microcircuit case, delamination). Engineers say they're more likely to experience this when using used ASICs that have been running for a long time past their warranty period. At the same time, relatively new miners have such problems less frequently.
Crypto entrepreneur Andrei Kopytov from St. Petersburg often faced the problem of burnt chips in used miners. In his opinion, problematic microcircuits can be seen before they fail during testing. He believes that the hash rate of problem chips drops sharply before failure, which can be overlooked when checking the total hash rate if a device that has been overclocked is used.
Old instead of new
In June about a fraudulent scheme that aims to deceive those who acquire new miners. According to the online publication, in a few months the demand for miners has grown dramatically and Antminer S9, S9i and S9j have become especially popular. So it is believed that the already mentioned S9 is most relevant today in the S9j modification at 14,5 TH / s, its cost is about 33-35 thousand rubles.
The essence of the scheme is that visually indistinguishable Antminer S9 with a performance of 13,5 TH / s are sold under the guise of new S9j at 14,5 TH / s, after re-gluing stickers on the device case and on hash boards. To increase profits, scammers often use old, exhausted miners, cleaning them of dust before gluing. Getting a less productive model instead of a relatively promising one, a crypto-entrepreneur who bought such an ASIC automatically runs the risk of running into burned-out chips as well.
Reliable data about the device can be obtained by verifying serial numbers, which is not carried out by everyone and not always. There is another way - measuring the real hashrate. Evaluation by firmware rarely gives results, as the software is often changed to a new one. Visually, the user interface does not differ from that of the new miner. Such firmware shows the user statistical data (βJacksβ and βHiksβ) in the web interface. At the same time, real statistics differ significantly from fake ones.
Another option is overclocking. Overclocked miners can sell as new+ or as old miners. The fact is that a miner with several burnt chips is used as the basis for the device. With the help of firmware, burnt chips are excluded from the circuit, and the rest are accelerated. As a result, the wear of the remaining chips (primarily due to overheating) increases many times - the cooling remains standard and over time the remaining chips also burn out.
Fraudsters with glued and overclocked ASICs often come across on Avito and other trading platforms. There are many Chinese and Russian shops selling "stickers". According to forklog, only in Moscow there are 5 fraudulent outlets selling such devices.
Purchase security
In principle, it does not matter which ASIC you decide to purchase. Regardless of whether it is new or used - when buying, you must clearly follow some rules. Let's call them conditionally βan easy way to buy an ASIC miner and not get scammedβ:
- Mandatory verification of serial numbers from the device board;
- Exclude devices with a suspiciously low price;
- Conducting a test for a real hashrate;
- Visual inspection for the presence of dust (especially in places where it is difficult to remove), the presence of dust is unacceptable in a new device and undesirable in an old one;
- Checking the mechanical performance, correct operation of the cooling, thermal performance (fan noise, even a used miner should not exceed the declared value, the temperature of the device must also be stable and within the limits specified in the specification.
Alternative firmware is also in high demand. For example, various custom software that can reduce power consumption. Stories about significant overclocking without significant threat to the device should be taken either as the incompetence of the seller, or as a deliberate lie.
What to do if the chips are on fire?
Many experienced crypto-entrepreneurs recommend that when buying a large number of miners, budget a soldering station and a hashboard tester in advance. These devices, with minimal knowledge and even hands (their own or a specialist), will allow timely identification of problem chips and replacing them with serviceable ones. This is especially true in cases where the owner practices overclocking.
Technicians from mining hotels claim that the main reason for the βdeathβ of chips is improper operation. Within the framework of the hotel, repairs can be carried out by the engineers of the mining data center, or competent specialists involved from outside. Sometimes there are reviews on the network about an easy-to-perform transplant from a βdonorβ miner. But this procedure does not seem appropriate given the prices of new chips.
Π‘onclusion
The main advantage of new ASICs compared to used ones is the warranty. When used correctly, it protects the owner from sudden death of the equipment or its elements. The main advantage of used ASICs is the price. If their resource is not developed and they were operated under normal conditions, they have a performance equal to new ones. But in case of technical problems, you donβt have to rely on the warranty (excluding devices sold during the warranty period).
It will not be superfluous in conclusion to repeat the basic principles of a safe purchase of a miner. When purchasing any ASIC, you need to check the serial numbers on the board, measure the hashrate, and ideally, use a hashboard tester. You should be wary in cases with unfamiliar custom firmware, and also be very careful with heavily dusty second-hand devices. Traditionally, I will be grateful for comments on the topic and any suitable additions to the material.
Important!
Crypto assets, including Bitcoin, are extremely volatile (their exchange rate changes frequently and dramatically), exchange speculation strongly influences changes in their exchange rate. Therefore, any investment in cryptocurrency - this is a serious risk. I would strongly recommend investing in cryptocurrencies and mining exclusively to those people who are so well off that if they lose their investments, they will not feel the social consequences. Never invest the last money, targeted significant savings, limited family assets in anything, including cryptocurrencies.
Photo used:
Source: habr.com