Mining: the technical part

The technology side of mining. The characteristics of AMD, NVIDIA cards, algorithms of mining, description of work of mining farm, software for mining, what to choose Windows, Linux or OSX for mining. All about mining.

Comparison of mining algorithms

SHA-256 and Scrypt mining

Due to popularity growth of Bitcoin at the end of 2013, the mining difficulty has increased for many times. This was also caused by the fact that many large investors began to buy ASIC equipment for Bitcoin mining on an industrial scale. It all led to the fact that SHA-256 cryptocurrency mining without special equipment ceased to be profitable (Bitcoin is the most profitable cryptocurrency based on SHA-256 algorithm for mining). For comparison, one ASIC unit on average had a capacity of 600000 Mh/s, and the most powerful GPU – ~850 Mh/s.This is why the mining of the scrypt cryptocurrencies started gaining popularity.The scrypt mining or GPU mining is not like Bitcoin mining because of algorithm differences. For mining of Litecoin, as well as its various forks on the scrypt algorithm, this article will discuss the important technical characteristics, as well as hardware compatibility, software and the most popular software – the miner, in particular the most stable and flexibly configurable CGMINER.

CPU and GPU mining

Now let’s make it clear the why graphics card (GPU) fits scrypt mining better than the central processing unit (CPU).The processor (CPU) was developed to make decisions according to the programs’ directions. Also, the processor performs a great number of other operations. The graphics adapter (GPU) is able to carry out many similar tasks very fast and effectively, but at the same time it switches to another task slowly.One CPU core executes 4 32-bit instructions per clock (SSE) or 8 32-bit instructions per clock (AVX), whereas a Radeon HD 5970 GPU is able to process 3200 32-bit instructions per clock (using its 3200 ALU or shader unit). It turns out that in this example a GPU can process 800 (or 400 (with AVX)) times more instructions per clock, than CPU.Even despite that since 2011 the CPUs have been produced with 6, 8 and 12 cores and clock speed of nearly 2000-3000Mhz and more, a Radeon HD 5970 GPU (with clock speed of 750 MHz) remains more than 5 times faster than four 12-core CPUs with clock speed of 2.3 GHz (while the price of the latter around $4700, in contrast to $350 for HD5970).

Mining on GPUs by AMD and NVIDIA

NVIDIA graphics adapters, due to their design features, are currently less capable and make farm building several times more expensive than with AMD solutions. For comparison – the most capable NVIDIA graphic cards have a capacity of ~150 Kh/s, AMD has 1500 Kh/s. But NVIDIA has a “Tesla S2070” card, which gives 700 Kh/s, however its price is $1360 against $510 for the most powerful cards by AMD.

Techniques of mining

How mining farm works

The main components of the farm are nearly the same as those of a regular computer, with several exceptions:

Motherboard. It should not be cheap and have 4 or more PCI-e slots (for graphics cards).
Processor. Its capacity is not needed for the scrypt mining of Litecoin and its forks. This is why the cheapest one is chosen, which fits the motherboard.
DDR memory. Size from 4Gb, the simplest and cheapest one.
Hard disk drive. Doesn’t play any role. It is needed to install the OS and to store wallets, so a simple flash stick fits.
Power supply. The main engine of the whole farm, so the choice must be done carefully and without hasty conclusions. The power supply capacity should be chosen with a margin of 150-200 watts, considering the power consumed by other components except the graphics cards.
Graphics card. The main and the most expensive component of a mining farm conducting calculation of hash functions of the blocks. Specifications and speeds of many graphics cards are displayed by users in tables on various portals. Here you will find links to them.
Cooling system. It must be well-designed to move the hot air away from graphics cards. In order to do this, the space between the graphics cards must be no shorter than ~8cm. Also, a water cooling system can be used – it cools the graphics cards better and doesn’t produce as much noise as air cooling, but is more technically complicated. Of the most sophisticated cooling system variants, we can empathize the oil cooling when all the hardware is fully submerged into a reservoir with technical oil (some “craftsmen” submerged the components into vegetable oil). An example of definition can be seen in this article.

There are currently a great number of graphics cards on the market, which suit for mining. The largest list of these graphics cards is available on [litecoin.info]. Here you can see the basic data of the mining: graphics cards’ specs and settings, but all of them are conditional, because every farm is being set up individually and depends on a great number of factors which will be considered below.Some graphics cards are already deprecated and they are impossible to find in the necessary number and condition. We will discuss graphics cards which are available on the market, as it will give an opportunity to make a mining farm of a necessary capacity. GPU mining, as well as the farm building, doesn’t have standard solutions, so your results on achieving the maximum capacity and stability depend on many factors, which are listed below.

Graphics card overclocking

The selection of optimal parameters of memory clock speed and core clock speed must be done individually for each graphics card. These parameters affect both the mining rate and the whole system stability. Also, overclocking affects temperature and energy consumption of the graphics cards. The more is the GPU overclocking, the more are the farm demands for the cooling system.

Hardware compatibility

If the system has different card series, or cards of one series but by different manufacturers, conflicts are possible during launch and overclocking, which will affect the maximum speed and the whole farm stability. Hardware combinations for a farm also affect the hash rate. A correct choice of farm components like motherboard and RAM also increases the stability and the mining speed of a farm. For example, as said before: the lack of standard solutions in scrypt mining leads to the fact that the same values and settings of the video adapters are often ineffective when applying to another farm configuration.

Mining farm building peculiarities

When building farms, one should do some calculations to know the most profitable variant. It’s necessary to calculate the total cost of the farm, choosing the most profitable components by profitablility and energy consumption. You need to know energy consumption of the whole farm and calculate 24 hours charges for energy. Considering these calculations, you can draw a conclusion on the payback period. To make this task easier, there are many mining calculators: from simple ones, which consider only the cryptocurrencies’ exchange rate and farm speed, to detailed ones, which consider exchange rate, speed, energy consumption, 1kWh, difficulty and exchange rate changes during the time.

Cloud mining

There are companies that provide their equipment capacity for a certain amount of money per month. This way is relevant for crypto currencies, which have only CPU mining. It is profitable in two cases: when the company provides a free trial period, or when the crypto currency complexity is low and the exchange rate is high.

Software

Operating systems and mining software.

Mining operating systems

OS installed on the mining farm may affect the crypto coins mining speed.

Mining on Linux

Popular OS for large mining operations. Small miners usually prefer Windows 10.Pros

Quick setup (5-10 minutes)
Occupies a little disk space (2Gb)
Support of up to 8 graphics cards
Doesn’t need to be activated

Cons

There may be difficulties for a beginner when using for the first time.
If you install the OS on a flash stick, it’s difficult to store big wallets.

Mining on Windows 7

Pros

Available and easy to set up and use for the majority of users

Cons

Supports up to 4 graphics cards

Windows 8

Pros

Available and easy to set up and use for the majority of users

Cons

Supports up to 5 graphics cards

Windows 10

Pros

Available and easy to set up and use for the majority of users
Many user friendly programs for overclocking, flashing AMD GPUs, mining
Doesn’t need to be activated
Supports over 13 graphics cards

Cons

Automatic updates can be destabilizing – however they can be disabled

Scrypt-Miner 1.2

The OS developed by «craftsmen», based on Linux. Monitoring tools are brought to the main screen. A detailed description of installation and setup is available here club.dns-shop.ru

Drivers

The right driver version choice is very important. Sometimes particular driver versions lower the total computational capacity of the scrypt mining equipment. At the same time the others, on the contrary, allow to achieve high hash rate. APP AMD SDK version must be 2.6 or higher, you can download an update for your system from the AMD official website.

Mining software

There are several main mining programs – bfgminer, ufasoft miner, diablo miner, phoenix, guiminer, cgminer. The most flexible in configuring, stable and informative miner is CGminer. So we will discuss it.

CGMiner

CGminer is managed via the command line. To ensure that you do not need to reconfigure all the settings every launch or when you change the cryptocurrency, it is easier to create a .bat file and write all the settings here. This file is created in the miner’s folder as a text document (notepad) with .bat extension. The basic setup for the miner to work looks like this: cgminer –scrypt -o stratum+tcp://east1.us.stratum.dedicatedpool.com:3351 -u user.1 -p x

cgminer – points to the executable
–scrypt – instructs the miner on the mined crypto currency’s algorithm
-o – after this, a pool address is specified stratum+tcp://east1.us.stratum.dedicatedpool.com: and a port 3351. This data can be found at all the pools, in “Getting Started” section.
-u user.1 – specifying the pool login and the created worker name
-p x – specifying the password for the created worker

Advanced settings to enhance the miner’s performance.

--auto-fan Automatically adjusts the GPU fan speed to maintained the specified temperature (value: no);

--auto-gpu Automatically adjusts the GPU clock speed to maintained the specified temperature (value: no);

--device (-d) Allows to select particular device for the work, everything works by default (example: --device 0);

--disable-gpu (-G) Disable GPU (value: no);

--gpu-threads (-g) Threads per GPU (values: 1 - 10, default 2, example: --gpu-threads 2);

--gpu-dyninterval Set the refresh interval in ms for GPUs using dynamic intensity (default: 7);

--gpu-engine Sets the GPU core clock speed, it is possible to set a range (example: --gpu-engine 900 or 800-900);

--gpu-fan Sets the fan speed in percentage, fixed or a range (example: --gpu-fan 25 or 25-65);

--gpu-map Map OpenCL to ADL device order manually, paired CSV (e.g. 1:0,2:1 maps OpenCL 1 to ADL 0, 2 to 1);

--gpu-memclock Sets the memory clock speed (for BTC it is better to lower the clock speed, for LTC – to raise it, example: --gpu-memclock 1800);

--gpu-memdiff Set the fixed difference in MHz between core and memory speed (example: --gpu-memdiff ???);

--gpu-powertune Set the GPU powertune in percentage;

--gpu-reorder Reorder graphics cards;

--gpu-vddc Change GPU core voltage, in volts (example: --gpu-vddc 1.125);

--intensity (-I) Aggression (intensity) (values: 10 - 14, d - dynamic, example --intensity 13 or d);

--kernel (-k) Specifies a kernel to work with the device (kernels: diablo, poclbm, phatk, diakgcn, example: --kernel diakgcn) (help is needed to select a kernel for card series);

--ndevs (-n) List all devices along with their numbers and exit;

--temp-hysteresis How much the temperature may differ from the target (default: 3, example: --temp-hysteresis 15);

--temp-overheat Temperature in degrees to reset core clock speed and raise the fan speed (default: 85, example: --temp-overheat 90);

--temp-target Set the target temperature in degrees (default: 75, example: --temp-target 80);

--vectors (-v) Set the vectors’ width, auto by default (values: 1, 2 and 4, example: --vectors 2);

--worksize (-w) Set the memory size, barely affects performance (default: auto, the value must be a power of 2 - 64, 128, 256, 512, 1024, 256 is recommended, example: --worksize 256).

Intensity is the key figure affecting the miner’s work speed, its value is set from 0 to 20. One must consider that a too high intensity can negatively affect the mining speed, because it MAY exhaust all available memory and actually reduce the mining speed in the best case. In the worst case – there will appear a lot of miscalculations and HW errors. Take into account that if the intensity is not set, CGMiner will adjust it itself, dynamically, to provide an opportunity of convenient work with the PC.Thread-concurrency controls an optimal volume of calculations which a scrypt algorithm can do. It is set up by default to use a few threads on all shader blocks the graphics card has at a maximum. The value must be a multiple of the number of shader blocks of the graphics card. So, if «thread-concurrency» is specified, «shaders» may be removed.It is recommended to spend some time to find the best value for your graphics card in order to get the best performance.

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