I'd like to install and run a BOINC project that I didn't choose yet. Never did it before.
My choice of the project will depend on whether it will run on my hardware/software (me having some demands too) or not.

So I'm wondering where it is better to start my help thread: here in the main BOINC forum or "there" in the project forum?

Hardware:
Odroid U3 ARM single board computer with 1.7GHz Quad-Core processor and 2GByte RAM, SD cart serving as hard disk ;)
http://www.hardkernel.com/main/products/prdt_info.php?g_code=g138745696275&tab_idx=2
passive chip cooling.
Running behind a TP-Link router.

OS:
Linux-Ubuntu

Welcome to Ubuntu 14.04 LTS (GNU/Linux 3.8.13.30 armv7l)

  System information as of Fri Dec 30 07:55:25 EET 2016

  System load:  0.0               Processes:           83
  Usage of /:   29.0% of 3.00GB   Users logged in:     1
  Memory usage: 7%                IP address for eth0: 192.168.1.101
  Swap usage:   0%

It is running headless (no GUI, command line interface) 24/7 and I use it as a Tor middle relay https://www.torproject.org/docs/tor-relay-debian.html.en
It's not CPU-expensive, most of the time less than 1% load, so I can spare cycles to BOINC.

I'd like to run a project with command line interface, input/output disk operations made in RAM if possible (saving SD-card lifespan) with the possibility of limiting the CPU load because of the passive CPU cooling .

Thank you.

Each project has an applications page that should identify if they support the CPU architecture and OS. However, when it comes to supporting their apps and getting them working it is typically best to ask in their forums. If it is just a question of installing the BOINC software, then it would make sense to ask here until you actually get to running the project apps.

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Check the project list to see what projects supports ARM+Linux devices. You are looking for Linux on ARM in Details there.

Running the device headless is no problem. BOINC client is a command line program and while all project science applications are technically command line programs you don't run them directly. The client manages running science apps. Typically BOINC client is controlled using BOINC Manager, a GUI program, but can be controlled using command line tool or with Manager remotely.

If the CPU runs too hot you can limit BOINC to use only some of the cores or you can tell BOINC to run the science apps only some of the time. You can set them either on project web site or locally. See Preferences.

You can keep BOINC's data directory in RAM disk but you'll need to keep an eye on the RAM usage of the projects you decide to join. 2 GB RAM on four core machine isn't much. You'll want keep a backup on a less volatile storage. If you keep using Ubuntu and install BOINC client from their repository then BOINC's data directory will be in /var/lib/boinc-client . I'd imagine you could mount tmpfs there.

Things become much clearer now, thank you both!

I'll try to follow Juha's recommendations.