the hub i'm using in that picture is the much discussed 12 port usb hub from saitechi. it wouldn't power more then 3 erupters...
Thanks. Amazon says that satechi hub is a 5V 2A hub.
So I guess we have to assume erupters are pulling more than 500mA or the hub specs are fudged.
Good to know. Better stick to 3.0 hubs then.
The Satechi hub is also specified as only being able to drive 250mA per port REGARDLESS of current supplied, so it may not even work with one BE USB.