"The GBS-8200 board drew a maximum of 0.4A"
Means it can be USB powered from a good USB power source. 
I think people sometimes have power supplies that don't put out enough power, but I think more often people have cables which are too long, too thin, or both, so even when something's connected to a 1 or 2 amp power source, the device still doesn't get the voltage it expects.
Some complaints about power may be related to the capacitor that's recommended to be swapped.
