Mining Monero on the CPU & Ethereum on the GPU

After his recently published article about mining Ethereum with AMD thread rippers in combination with four RX Vega 64 GPUs, German Phoronix reader Thomas Frech is back with another guest post. This time he talks about his adventures mining the Monero cryptocurrency on the CPU while using the GPUs for Ethereum mining.

It turns out that mining Monero / XMR on the CPU is much more profitable than Ethereum on the Radeon RX Vega-64 when using the closed source ROCm stack AMDGPU-Pro 17.30.

The good part is that the ROCm stack is already fixed in the open source driver. “Initial feedback is that the latest ROCm (1.6.3) includes the performance fixes, but there will be a version 17.40 shortly that will include them.” commented by AMD’s John Bridgman.

And for the people who want the closed source driver and can’t wait for the 17.40 release, there is a beta driver available.

The xmr-stak-cpu miner turns out to be the best Monero CPU miner, but it’s a really bad trap: if you set the donate-level.h to “NULL” it will work to a very poor performance of only 10-20% The best setting if you don’t want to reveal the default 2% setting is to convert it to 0.1%. With this setting, the bad result will not be shown as the 0% option.

I compared 4 systems with Monero, a 1900X, a 1920X and an FX8320 as well as an 8xARM Cortex-A53 MediaTek MT6750 smartphone.

The result for the 8xARM Cortex-A53 in a Playstore Monero mining app with 7 threads is ~ 6-8 H / s

The FX 8320 with 32 GB 4 DIMM DDR3-1333 MHz RAM and 7 threads ends up with ~ 130 H / s

The 1900X with 1 DIMM 16 GB 2333 MHz with 8 threads reaches ~ 650 H / s

And the 1920X with 1 DIMM 16 GB 2333 MHz with 12 threads reaches ~ 600 H / s

What is very interesting is that the xmr-stak-cpu miner is allergic to Intel’s hyper-threating if someone uses the full 16 threats on a Threadripper 1900X. The result is only very bad if you only use 1 thread per real core you will get full performance. Instead, the old architecture of the AMD FX-8320 does not slow down if you use more than 4 threads. So if you use 8 threats on this 8 integer core CPU with only 4 FPU and SIMD units, there will be no slowdown. This with Monero Intel’s hyper-threating is a joke.

It is also very interesting that the 12-core 1920X on 1 RAMM DIMM is slower than the 8-core. I think this is the result of the very strong latency sensitivity for 12 cores for which you need more than 1 RAM DIMM in order not to slow down CPU on Monero.

The moriaxmr.com mining pool is very good, it has low fees and the statistics software of the website’s monitoring system is really sheer excellence.

At the moment, the performance of the 3 systems at Monero with the CPUs is around 50 € per month, and this is currently much better than the GPUs.

My GPUs on Ethereum really need the new 17.40 driver, so I’ll be writing a third article with a full new test on Ethereum. Right now I’m only getting ~ $ 50 a month for six Vega graphics cards. Only six because of cooling problems I can only operate 3 cards per desktop PC with good cooling and for that I have to install the lower GPU cards like a cheater Asland. With 4 cards per pc, it is simply impossible to get airflow into the 2nd card from above, even by mechanically cheating like handing out the cards to get airflow.

In the future I will also write about energy consumption, but I have to buy a new power meter because my old one is broken. A few more words about the hardware I’m using for this project:

Power supply: SilverStone Strider Gold S-Series 1500 W ATX 2.3 (SST-ST1500-GS)

With 4 years of training as an electrician, I can say that this is the power supply you need for your desktop PC.

It’s ready for 4 AMD VEGA 64 GPUs and even ready for dual socket systems with 4 * 4-pin / P4-12-volt lines, meaning full 2×8-pin, and that’s what you really need for an AMD Threadripper system or an IBM POWER9 dual socket mainboard. It’s completely modular and even has two cables to hook up than you need. So if you need more SATA you can choose this cable, or if you need more old school Molex 5V + 12V cables you can choose the other cable.

CPU cooler: Arctic Liquid Freezer 120

The Freezer 120 is really an easy to use and cheap (57 €) CPU cooler. From my point of view, it has a very low temperature. I won’t go into details in this article, but my 2 ThreadRipper CPUs 1900X / 1920 can stay on the highest XFR modes (+ 200 MHz) all the time. This means you won’t need a larger cooling system for the 8 and 12 core unless you manually overclock the system.

Case: Lian Li PC-7HA silver

What a beauty of a case and it brings very good quality for the low price (75 €). It really has a lot of design wins. I made some modifications to an additional 120mm fan on the front to replace the 3 x DVD 5’25 “slots to get extra fresh air to the CPU. I also removed the hard drive case inside to add a to achieve better airflow, and with M.2 SSDs on the mainboard I don’t need a silence case for old hard drives.

Next time I’ll be testing the 17.40 driver and possibly the open source ROCm stack as well.

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