On some setups, you do want some power on those USB connectors, and that's my case since I run a UPS on my main desktop PC. In a power outage, there needs to be some trickle power on the USB port in order for the UPS to switch over from AC power to Battery Power. If a human being isn't there in front of the computer when this happens, the PowerChute UPS software uses signals sent between the computer and the UPS to initiate an orderly software shutdown prior to the Battery discharging, and the PC crashing as soon as the battery runs out.
I run my PC on 24x7x365 (minus a few days when I leave on the house for extended periods of time), so even if my PC is shutoff with it's power switch, it's still protected from power outtages,
but since windows isn't running when the PC is switched off, it can't perform a software shutdown, but it's the next best thing as when the UPS shuts down, it filters surges through the power line which connect the PC to the AC outlet.
When my PC is running and I'm gone for a few hours from the house, the PowerChute software will perform the orderly shutdown via windows and signals sent to the Motherboard from the UPS via USB, so in this case that's very handy to have some power on those USB ports
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