well, first off unless very far lengths, any hub will work with no power cable so them working with hub unplugged does not prove that they are drawing power while its in sleep mode. the time difference does though. you can turn off usb ports by going to device manager and clicking properties over a port and going to power management tab and checking the box next to "allow computer to turn off device to save power". however, you can only do this for ports on laptop, meaning you cant do something specific with 1 port on a hub and leave the rest off. you will have to plug your touchscreen into one of your laptop ports.