Do AC-powered USB hubs provide power when the computer isn turned on?
To establish a power connection, USB cables need to have a session with a computer established so the device can communicate what voltage to send. Most hubs can’t do that on their own, they lack the processing power. Specially designed plugs can have the voltage level pre-set and hard-wired, so they can go directly into an outlet and provide power to the device they were designed for, but not others.
