USB device has exceeded the power limit
hmmmm ... I read all the posts here and learned a few things (400a vs 500a) and etc. I have disconnected EVERYTHING that is USB, rebooted and STILL get the freaking message. Now what?
Ok firstly what device are you trying to connect to a USB port ? USB is only ever really intended to send / receive data at low voltages.
Some USB powered hard drives lately (high capacity ones usually) require a second USB connector.
Also not all USB headers / connectors can supply exactly the same voltage.
For anyone to help you please post some more info - ie device being used, if the USB socket is on the mobo or its via a case mounted socket or even a usb hub