Hello,

i own different devices running on different platforms. So decided to compare there boinc performance using the same project. The chosen project was yoyo@home, because it does has work available for Android, Linux, Linux on Arm and Windows. The downside is that work packages take a long time to finish. To (hopefully) reach a stable RAC all devices were running 17 days for 27 hours a day. The electricity consumption was measured with the same devices and when the consumption was fluctuating 1 watt up/down i used the higher value. The consumption is including the power supply. For Laptops the screen was off and the wlan on. None of the laptops has an AMD or Nvidia graphic card.

The compared machines are:

A Raspberry 3 with active cooling running rasbian.
A Laptop with a core i7 3632QM running @ 2.0Ghz on 4 cores and Win7 (Refurbished - category B).
A Pentium J4205 (Asrock Board) running @ 2.4 Ghz on Ubuntu 16.04.
A Nexus 7 Android tablet with USB cable soldered to the battery charging electronics (battery died long time ago) with a fan blowing on the tablet to prevent the CPU from throttling.
An Odroid XU 4 running @ 1Ghz for all 8 cores to avoid throttling and system freezes. Its running the Hard Kernel Linux and has an customized passive cooling .
2 Laptops with estimated yoyo@home performace. Those devices run Word Community Grid (WCG) and i compared the performance against an i7 3632QM laptop running WCG. The estimated is that yoyo@home scales similar to WCG. The laptops have an Intel U7300 @1.3 Ghz or an Core 2 Duo T8300 @1.6Ghz.

Further i included the investment for the different devices. For the Nexus 7, i7 and U7300 laptop those are prices from Ebay for used devices. For the Odroid and Raspberry the prices are what i paid for a complete running system. You may be able to build a few things slightly cheaper, in particular when you can use old parts. I did not find a Core 2 Duo T8300 laptop for sale.

All investigations are collected in the following table:

https://steemitimages.com/DQmYwygyJk83pR1SaVMbC52omKbcAa2ZMvHKd5ppVGJarVo/table2.PNG

It can be seen that the old laptops are no good choice in terms of performance per watt of per €. The most efficient is the Odroid running @1 Ghz while the i7 laptop offers the most performance per invested €. The Nexus 7 and the Rasberry are similarly efficient. However, if you want to run the Nexus 7 24/7 you have to remove the remove battery and do some soldering.The Pentium J4205 is a good choice for a passive system when you have have an spare disk and power supply. This could reduce the investment to about 120€, which would make it the best choice. My favorite is the i7 laptop - since it is a complete system with disk, power supply, battery and screen. This makes the system install and monitoring rather easy. Further laptops can survive short power outtakes.

I found i really interesting that there is no device in the list which is significant more efficient than the others. Unfortunately i have no last generation smart phone which i can run 24/7 to add to the statistic. If somebody can provide some numbers i would be really interested to extend the table.

best

Lars

Edit: as reported below by "sodom" a RAC of 700 can be reached with the Raspberry 3. This would give 120 points per watt or 12 points per €.