Monero RandomX: PoW performance on new AMD Ryzen CPUs
Mining

Monero RandomX: PoW performance on new AMD Ryzen CPUs

By Emanuele Pagliari - 24 Aug 2019

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Over the last few months, the community of Monero has been strongly discussing the currency’s new Proof of Work mechanism called RandomX.

This Proof of Work is expected to make its debut in the Monero protocol next October during the classic six-monthly update fork and it currently offers interesting performances on the new AMD Ryzen 3000 processors.

This new Proof of Work mechanism will once again eliminate ASICs and FPGAs from the mining of the cryptocurrency. In addition, the mining revenue from video cards will drop drastically, allowing (given the efficiency) only CPUs to be used for mining, at least initially.

In recent weeks, the first RandomX-compatible mining tools have been made available, allowing users to directly evaluate mining performance using Monero’s future PoW.

From the first tests, an interesting performance advantage has been gained by AMD Ryzen processors, in particular by the third generation of CPU based on the ZEN 2 architecture, which debuted last July.

These CPUs, in fact, boast large amounts of first, second and third level caches, practically twice as much as the first and second generation of AMD Ryzen.

The new anti-ASIC Proof of Work of Monero

Monero has always shown a certain resentment towards specialised mining hardware from the outset.

In the last two years, in fact, the coin has undergone three forks, the last of which took place on March 9th, with the aim of making some changes to the Proof of Work based on CryptoNight so as to exclude once again ASICs and FPGAs from the mining of the cryptocurrency.

As of last February, the developers of the coin have been working on the new Proof of Work RandomX, with the aim of rendering the mining of XMR egalitarian again. RandomX, according to the software engineers who developed it, is designed to be CPU-centric

The common processors of modern PCs, in fact, have a hardware architecture that allows to carry out all possible operations, using a series of native instructions in their ISA (Instruction Set Architecture). 

There are several ISAs, some used in desktop processors (x86), others in mobile ones (usually ARM), characterised by a rather reduced ISA to maximise efficiency (RISC).

Unlike CPUs, ASICs (evolution of FPGAs) are able to perform one or a few operations for which they have been designed ad hoc, guaranteeing extremely superior performance compared to a generic computer processor.

Since Monero’s goal is to ensure maximum decentralisation, the RandomX development team has decided to favour CPUs as they are the most widely distributed IT resource in the world today.

However, the algorithm’s design choices will also severely penalise GPUs, which are currently widely used in Monero mining.

In fact, the GPUs used in graphics cards are processing units that specialise in performing parallel and very sequential tasks. Unlike CPUs, therefore, they cannot be used to perform any operation, but only for highly parallelisable, sequential and repetitive functions.

It is estimated that with the activation of RandomX, CPUs will be at least three times more powerful than GPUs when mining Monero.

RandomX: the performance of the new AMD Ryzen 3000 processors

Looking at the first tests on the new AMD Ryzen 3000 processors, some interesting results immediately emerge.

The AMD Ryzen 3600 processor, a solution with six cores and 12 threads operating at a baseline clock of 3.6 GHz but capable of rising up to 4.2 GHz, is able to obtain an excellent hashrate, reaching almost 6300 Hash/s.

This CPU is currently sold for less than 200 euros and has very low power consumption, thereby achieving the best hashrate/price ratio. Users, in fact, have reported an average power consumption at the factory settings close to 110-120 watts of the entire system (80 watts for the CPU only).

By overclocking the processor, it is possible to reach 6700 H/s, although the power consumption doubles. Just to make a comparison, the old 6-core Ryzen 2600 from last year is unlikely to reach 4000 H/s, with slightly higher power consumption.

After the 3600, the AMD Ryzen 3900x is the CPU most preferred for mining Monero on RandomX. With 12 cores and 24 threads with a baseline clock of 3.8 GHz, this CPU can double the performance offered by the 3600, reaching a hashrate close to 11500-12000 H/s.

Obviously, the power consumption goes up, touching 180-190 Watts, with absorption by the processor alone close to 150 Watts. The price also rises, since at present it is difficult to find the Ryzen 3900x at less than 550 Euro.

Applying a moderate overclock to the CPU it is possible to push it up to 13 thousand hash/s, although the power consumption increases dramatically (280 Watts for the entire system).

The third best-selling processor in the AMD Ryzen 3000 family is definitely the 3700x, equipped with eight cores and 16 3.6 GHz threads with 4.4 GHz turbo, which in the first tests manages to reach a hashrate between 7500 and 7800 H/s, with the CPU alone consuming close to 110-120 Watts.

Also in this case, by overclocking the processor it is possible to reach 8300-8400 Hash/s, on condition of accepting a 50% higher power consumption.

At the moment there are no benchmarks of the AMD Ryzen 3950x processor, perhaps the most awaited solution on the part of crypto miners, as it is equipped with 16 cores and 32 threads with a baseline clock of 3.5 GHz, but able to rise up to 4.7 GHz, all while maintaining power consumption close to those of the 12 core solution, given the same TDP.

This CPU will debut at the end of September at $750 and could very quickly be sold out, due to the low quantities and high demand.

It is estimated that the 3950x can easily reach 14-15 thousand Hash/s, keeping the consumption of the entire system within 200 watts. The overclocking potential is unknown, however, it is likely to reach 16,000 Hash/s rather easily, although consumption would increase significantly.

The best CPU for RandomX? The Epyc 7742

At the beginning of August, AMD also revealed the ZEN 2-based processors for the server market. Among them there are solutions such as the Epyc 7742, equipped with 64 cores, 128 threads and 256 MB of L3 cache that, combined with a clock close to 2.5 GHz all-core, allow this CPU to reach a hashrate close to 39 thousand H/S with a very low system consumption, less than 350 Watts (250 Watts for the CPU only).

The result is, therefore, a much more efficient solution even than the 3900x, but the real problem of this piece of hardware is the cost.

The AMD Epyc 7742, in fact, has a price of just under 7 thousand dollars, with costs related to the platform and the need for octa-channel memory that significantly raises the price of a PC based on this CPU.

However, there are also other models of AMD Epyc processors with 64 cores, including the 7702P, which has a slightly lower clock than the 7742 and can only be used in a single-socket configuration. This CPU, in fact, is sold for 4400 dollars, making it much cheaper, but still extremely expensive for mining.

Waiting for Threadripper 3000

The most diligent miners are currently waiting for the third generation of AMD CPUs of the Threadripper family, which has always been characterised by higher frequencies than the Epyc counterpart for servers despite having a similar quantity of cores, as well as much lower prices.

The third generation of Threadripper should be made available before the end of the year and, according to the latest rumours, it will boast up to a maximum of 48 cores and 96 threads for 250 Watts of TDP on the top of the range CPU. The price per hour is unknown, even if, considering the prices of the server variants, this CPU could be in the market range between 2000 and 2500 dollars.

Whereas the other cheaper models should range from an entry-level solution of 16 cores, which will be made available between 700 and 800 dollars, to solutions with 24 and 32 cores, placed between 1000 and 2000 dollars.

It is impossible to predict the frequencies and therefore the mining performance, although the decision to limit the top of the range to 48 cores would have been chosen to allow higher frequencies compared to the server counterparts.

It is very probable that, seeing what AMD has done in the past thanks to the higher frequencies, the third generation Threadripper solutions can obtain better performances than their server counterparts, even by several percentage points, while costing much less.

All that remains is to wait for the announcement and the first tests, though this is unlikely to happen before November/December 2019.

Emanuele Pagliari
Emanuele Pagliari

Telecommunications engineer with a strong passion for technology. His adventure in the world of blogging started on GizChina.it in 2014 and then continued on LFFL.org and GizBlog.it. Emanuele is in the world of cryptocurrency as a miner since 2013 and today he follows the technical aspects related to blockchain, cryptography and dApp, also for applications in the Internet of Things.

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