What happens if you under/overvolt a USB hub?

[Othersider]

If I take your typical cheap USB hub, which is marked with 5V at the power supply port, and give it 4.5V or 6V, what will happen? Is there any kind of power regulation at all in most hubs, or is it expecting 100% clean 5V from the transformer?

 

[AceGoober]

Depending on the peripheral(s) that you have connected to the hub, and the circuit design, they will either barely function, or cease to power-on with low voltage. At high voltage, I would gander to say that they would probably cease to function, permanently, and possibly cause damage to the peripheral(s) that you have plugged into them.