Got my R909 unit yesterday.

It was equipped with an Artic F8 fan, that has a good airflow : 52.7 m³/h at 22.5 dB
Replaced by a Noctua NF-A8 PWM : 55.5 m³/h at 17.7 dB

Plugged it to a Raspberry Pi 3 Model B, Quad Core CPU 1.2 GHz, 1 GB, with Raspberry Pi OS Lite.
It's using around 38~40% of the CPU. Edit: The CPU percentage goes to 400% on my model. See Kano's explanation here (link).

I've turned the voltage knob clockwise, to add voltage.
It's running at around 2.061 Th/s for 99 watts at the plug (including power supply, Raspberry Pi and R909).