I don't understand the purpose of these USB miners.
They will never make ROI, plus don't they have to be controlled by a computer?
And how much power does that consume?
Depends on the computer. My tinker toy is a 60w headless xubuntu nettop.
BBB or raspi draw next to nothing.
Power hungry PCs are being replaced in many segments of tech, not just mining.
ROI - not beating that dead horse today.