Environmentally Responsible Cryptocurrency - Part 4

Benchmarking, Performance and Power Efficiency

February 3, 2018
If you haven't read the first part of this series of articles, you can go the beginning here: Environmentally Responsible Cryptocurrency.
The optimal implementation of an democratic energy efficient cryptocurrency system should be one that balances performance, cost and power efficiency. If performance is too low, it won't be useful. If overall mining cost is too high, it will have too high a barrier for the masses to invest in. If power efficiency is too low, it won't be able to be powered by freely available environmental energy, e.g. sun, wind, tides, etc.
Existing CPU cryptocurrencies improve democratization by making ASIC or GPU mining impractical. But the plethora of alt-coins out there and the casualties of the marketplace have shown that the market is probably not quite ready for a CPU and memory intensive cryptocoin. Nonetheless, we'll look at how one of the existing CPU coins, Con Magi (XMG) does on some low power platforms and compare to running on a medium powered Intel system.
Let's take a look at Coin Magi (XMG) performance on some lower power platforms.
Here is a Raspberry Pi Zero W at idle running at .5 Watts (0.097 milliamps * 5.13 volts)

While mining XMG (Coin Magi) it runs at about .83 Watts (0 .162* 5.12) doing about 0.7 Khash/s. That works out to about 1.2 mW per hash per second.

Here is my Raspberry Pi 3 with AArch64 clock at 1.2Ghz (default clock speed) running idle at 1.36 Watts.

Here it is running 4 threads at around 4.1 Watts. It does about 10 khash/s. That works out to around 0.41 mW per hash per second.

So the RPi3 is about 3 times more power efficient for XMG mining than the RPiZeroW.

An Intel i7-7600U @2.8GHz tested idle at 6 watts.

With 4 threads mining, it ran 25 watts and was able to compute about 40KHash/sec. That ends up costing 1.6 mW per hash per second
It's interesting to see that for M7 hashing, the Raspberry Pi 3 is the most energy efficient. However, it is at a 3.5X hardware premium compared to the Pi Zero. The Intel gives 4x performance at a 6x efficiency penalty and a 30x cost penalty. Granted this is not apples to apples since I compare a bare RPi system against the cost of a laptop. But Raspberry Pi is also utilizing much older chip production nodes, so I think it is close enough for illustrative purposes.

System	HashRate (H/s)	Wattage	Hash/watt*sec	System Cost $
Raspberry Pi Zero W	700	0.83	843	10
Raspberry Pi	10,000	4.1	2,439	35
Intel Core i7-7600U	40,000	25	1,600	1,300