One way to find out how many amps your device(s) use, is to go into control panel, select device manager then look for Universal Serial Bus Controllers and select one of the USB Root Hub listed, click on POWER to find the device and look at the amount of power it's using. For example , my Keylab Essential 49 uses 100ma and identifies as USB Compliant Device.
My Keystep uses the same 100ma.
At least you'll know how much power you're using. Also, in the header of the USB root hub, you'll see how much power is available to all ports in that particular hub. If the hub supports 5 devices and you have 4 ports using 100ma, the 5th would be borderline. If that's the case, you could try another hub on your motherboard. Most newer motherboards provide for a lot of hubs but many are not connected internally. You could connect a USB extension to one of the available ports on the motherboard and bring it out of the computer to attach your controller. Might help.